When posssible, it's best to prune all these in late winter or early spring. Here, maybe the last week of Feb. Pruning now will stimulate new growth which will be harmed by any hard freezes.
Transplanting will be best done after the first freeze, which could be as late as December.

eldo1960 is right....plus anything you cut back very much right now will just look bare and twiggy for several months. Be sure and prune the hollies late winter or VERY early spring so you'll get more flowers and berries. Hmmm...never had a salvia greggii die after pruning, but I've certainly set them back by cutting them back too much all at once when they were big and very woody. I guess I've had the best results from just shearing them all over lightly, maybe only 1/4 to a 1/3 back at a time. I'm thinking maybe part of the trick is to not cut back behind where there are leaves?

And anything that needs planted (as opposed to transplanted) this is a perfect time here.

I'd like to make a suggestion. I'm not dodging your question, but you could do some permanent damage if you prune incorrectly... especially to a crepe myrtle. Can I recommend that you contact your County Ag agent's office there and discus this with them. They may even have some information on pruning for you. Whatever you do, DON'T top the crepe myrtle... ever. The others can recover.

Just a suggestion,
Xtal

good additional comments from briosafarm and xtal. In colder climates, new shrubs and trees go in in the spring, because the roots need to get established before the extreme cold which could kill them. But in Texas, the ground is always warm, so the roots have all winter to develop and you get almost an extra year's advantage by planting in the fall.
I should have picked up on the crape myrtle thing, too. Light pruning anytime is fine. Maybe there is a stray twig growing the wrong direction that needs to be removed. This is simply tidying up the plants.
If a tree-form crape myrtle is wanted, then when it is still fairly small, all but maybe 7 limbs are removed clear to the ground. That leaves enough so that when it gets big enough, you can decide which 3 or 5 will make the nicest, most symmetrical "tree" an you remove the rest, leaving one extra in case one gets damaged and has to be removed. As the plant matures, you will want 3 or 5 main trunks, and the rest will be cut off to the ground. On these trunks, the extreme lower twigs/branches are removed to make the plant look tree-like, but don't make the mistake of stripping any trunk up too far. If you do that, no new branches will ever grow back. All growth takes place at the ends of the growing tips at the top.
Lastly, TOPPING crapes is epidemic across the South, for reasons that elude reasonable people. Topping is cutting back the upper limbs severely. It makes no sense, is counterproductive, and when the crapes are bare in the winter, the thick limbs below and the skinny regrowth above is one of the ugliest sights in today's landscapes. Rather than rave on about topping crape myrtles, which some clever horticulturist dubbed CRAPE MURDER, do an internet search on the proper pruning of these plants and read several articles. You might even try entering crape murder and see if that comes up.
WHEW! I got on a soapbox.
Good luck in your Texas gardening.
Actually, I live only a few miles from China Spring. I would suggest that you listen to Neil Sperry on AM radio KRLD 1080 from 8 to 11 on Saturday and Sunday mornings. His book, Texas Gardening, is a very good handbook, although it is becoming outdated, as far as the introduction of new plants since it was published, and some revised recommendations on lawn fertilizing and a few other things here and there. I can suggest some other books if you are the type to read for gardening advice.
I also feel the need to warn you that Waco is limited in our choice of nurseries, and some of the leading ones give advice that is often questionable and often plain wrong. It is best to do your research on your own. Texas A&M website has much accurate information. They have a list of SuperStar plants for Texas, which have undergone rigorous testing in order to be given the designation.
If you can visit the Dallas Arboretum and the Ft. Worth Botanical Gardens, you can also see plants suited for Central Texas.
Bonnie's Greenhouse near Bellmead is a great place to shop, and Bonnie knows her stuff. It's fun to visit.

Thanks everyone:

Yes, I know enough not to murder my Crapes. I've been training them into tree form pretty much as described above by thinning and shaping. What I was more curious about is WHEN is the ideal time to pull out the snips.

I just watched the commercial landscapers totally cut back all the landscaping around our subdivision's front gate and gatehouse last week. They sheared all the shrubs back to little nubs (salvia, lantana, and assorted hollies) and cut the crapes way back. Then came through and put down about 4" of mulch. Seemed to me that it was WAY too early to be doing such a severe haircut.

What I have now are some wax myrtles and oleanders that have gotten pretty leggy and overgrown. They are providing various visual barriers around our backyard so I want to cut them back to some extent so that they fill out fuller next spring. I was thinking of doing that around new years or a bit later after all the oak leaves have for certain dropped. Then I can mulch everything without fear that it will all get covered with leaves again.

I also have a lot of salvia greggi and lantana that are still blooming but pretty overgrown. How and when should I cut these back to provide the best growth next spring? Or should I just leave them untouched?

I have a lot of those generic dwarf yaupons and dwarf burford hollies that could use a bit of shaping. I figured mid-winter for that work as well.

Finally I have 3 medium-large pride of houston yaupon hollies that I want to move and form into more of a tree shape. Again, January?

Oh, eldo...I've discovered Bonnie's Greenhouse. I've bought dozens of flats of salvia greggi and yellow columbines from her. I've had the most success with those two plants when it comes to perennuals. The salvia in sun and the columbines in shade. Most of the rest of the things I've experimented with haven't lasted more than one season.

My newest thing is yucca and native grasses. I've been going back through my yard and putting in more native xeroscaping type of plants. I have St. Augustine grass which requires some water but I want my flower beds to be planted with stuff that doesn't require any MORE water than is required to keep the grass minimally alive during the summer. Trial and error (lots of error) is getting me slowly in that direction.

I was driving from Rockport to San Antonio, this morning and was listening to Bob Webster on the radio, and someone asked the question on when to trim crape myrtle, and oleander. Bob Webster said you trim Oleanders in the Summer after they have their first blooms in May or June. He said if they get frost bitten then of course trim them in the spring, but you will loose most of your blooms. The crape myrtle, he said to just dead head the blooms, not to trim from the top, if you need to do that, then move the plant, and replace with a dwarf crape myrtle. This will prevent crape murder.

Yeah, I was wondering about the Oleanders because they bloom on 2nd year growth and the stem tips that will have next year's blooms are already formed. Same thing with Texas Mountain Laurel but then those plants grow so slow who needs to prune them.

My crape myrtles need more then just deadheading the blooms. There are too many tangled and twisted branches going all directions in the center of the trees. They need to be thinned out somewhat to give them more room to grow and better shape. It's not a total size issue, but an issue of too many suckers and branches in too small of a space. But I have no intent to chop them down to toothpicks like so many landscapers do around here.

I need some help regarding cutting back overgrown dwarf yau[pon holly. We moved in to this house 2 years ago and in front of my house are dwarf yaupon holly that are so tall and skinny. Can I severely cut them off and will they grow back?
I appreciate your suggestions!
Agie

Some varieties of yaupon have been bred to be tall and skinny as a vertical accent or screen - one is called 'Will Fleming'. They cost a lot more than the little bun-shapes - is it possible this is what you have?

Annie

No they are really the dwarf ones, I think the previous homeowner did not really prune them or shape them that's why they just became so tall and at the same time they are unshaped. I have 10 of them in front of my flowerbeds. I like them but they are not attractive, as compare to the other landscapes they are round and small.