Phew...that is some severely skewed soil.

I'd skip on the N amendments until closer to spring planting given that you're most likely in an area that doesn't experience cold winters, but the pH could use some immediate attention.

There are very few acid loving crops that will grow in the 4.5 range...well, potatoes and blueberries, but neither are winter friendly.

Most winter/colder crops like a pH around 6.0...turnips, carrots, and parsnips are an exception, but still like it closer to 5.5 than 5.0 or less. I dunno if your winters are mild enough to crop them.

So, think I should apply lime now and not plant anything till spring?

You guys think I have a shot at anything growing reasonably (greens) if I till in lime now and plant immediately afterwards for a fall garden?

Guess real question is, will applying the lime now have any chance of raising pH in time for making a fall garden successful this year?

It ultimately depends on the type of lime and how finely it's ground (along with other, more minor soil considerations) to how long it takes for a noticeable effect.

That said, most pulverized dolomitic limestone takes 2-6 months for best effect depending on fineness of particles, moisture, and soil type. It's generally closer to 4-6 months than 2-3 months in most soils.

I agree with NC - lime and P additions now, hold on the N if you have that separate. The pH will take 3+ months to stabilize. That in turn, will affect the P levels. Any N you add now will be gone in weeks, before the pH stabilizes. The N addition won't hurt anything, but it won't help.

If it were me I'd work on getting the soil right for spring, and save my time, effort and money this fall. I know it's frustrating, but you'll probably be saving some wasted effort.

That is the type of weathered loess that is common in MS. Not only you will have to apply lime this Fall (right now), you will have to apply some lime every Fall, basically forever. Starting next spring, you should be able to crop the garden, including in Fall. Most crops will grow after the first initial liming.

But if you have access to wood ash, that would be perfect for your site instead of lime. It is alkaline (10.4), fast acting, and contains both K and P in sufficient amounts (3-7% and 1-2%). For 1200 sqft, a good yearly dose would be 50 lbs of wood ash. Do plant some blueberries in parts of the yard that will not be limed, and you should still manure or compost the garden. I have no idea what cover crop can grow there. surely not grains, clover, or lava.

Guys, thanks for all the good info. I'll probably save myself some heartache and not do a fall garden. I'll have to ask around about some wood ash.

I'll dig around and see if I can find a good acid loving cover crop. Another idea would be to drag a chicken tractor on top of it and let the chickens 'fertilize' it for me all winter.

To add to the sting, I paid good money to have this top soil hauled in, garden was a bit of an afterthought, but I suppose this sort of soil is common for south MS.

Spend this fall preparing that soil for next spring.
How much organic matter is in that soil?

Some wheat's, cereal or winter Rye, the vetches, winter Barley, or may Austrian Winter Peas are some of the cover crops that tolerate acidic soils, but most all of them need to be planted when the weather is cooler, so you have a couple of months yet to work on amending that soil and controlling any "weeds".

I think you have a number of options for cover crop, especially a few weeks after the liming. You might find something useful from the link below. They're in central FL and very reputable.

Here is a link that might be useful: Cover Crop Seed

Ended up getting
Aeschynomene Seed - 1 lb. bag
Sunn Hemp Seed - 1 lb. bag
Also have 5 lbs of Austrian Winter Peas

Not sure which one or what combination to plant and when, but I'll figure something out between the 3 of them.

Sun Hemp is pretty cool. Suspect you'll be in great shape come spring.

Here is a link that might be useful: Sun Hemp

This article may answer some questions about liming soil.

Here is a link that might be useful: Liming soil