there really is no bad time to aerate altho the turf will benefit most when done in the spring. if you arent going to properly prepare the seedbed for the new grass seed then aerating will certainly help. throw the grass seed right before you aerate and run the machine in crossing directions. the soil cores it brings up will cover some of the seed. be sure and keep the area moist until the seedlings are a month old.

Core aerating and seeding go hand-in-hand as second to preferable seeding methods. The reason is the exposed cores provide an ideal condition for seed/soil contact. Plus, as the cores mulch themselves back into the soil, they carry the seeds with them. Is that what you're asking?

The growing seasons, which are the periods of active growth, is when you want to core aerate. So, your timing is ideal. The only thing I would suggest is beginning your process as soon as possible. Rather than waiting until the end of the month, make it mid-August if you can. I say because this is also the season to battle Poa, and just killing it off and overseeding is not enough. After the new grass is established and has been mowed 2-3 times, apply a pre-emergent herbicide that is labeled for controlling Poa annua, like Balan, Dimension, or other (whichever also offers post-emergence effectiveness) or something like Prograss (very, very expensive) as soon as possible. Check herbicide label for exactly when application after seeding can take place. Incidentally, core aerate and overseed the whole the lawn, not just certain areas.

Here is irrigation schedule for the seeds
water 15-20 minutes twice a day for two weeks
water 20-30 minutes once a day for one week
water 30-45 minutes once a day every other day for one week
water 30-45 minutes once a day twice a week for one week
move into deep irrigation, increasing the time to provide 1 inch of water all over and decreasing the frequency to just once a week.

Starting off, the schedule supplies roughly 1/4 inch of water, then increases that amount while decreasing frequency of application at the same time. Like practically everything that concerns lawn care, this schedule is a general guideline and should be modified to accomodate your specific conditions. The lengths of time should be modified if you have an automatic sprinkler system since that will not take as long to provide adequate moisture. So, decrease amount of water (time) but maintain frequency as is. The tuna cans test is recommended. If it is still especially warm, you may want to irrigate 3 times a day (10-15 minutes if necessary) for that first couple weeks. Your objective is to keep the upper 1 inch of soil moist and not let the seeds dry out.

Baby the grass for the rest of year. Once the seeds begin to sprout, don't walk on it if at all possible.

gryd,i am also in ct and last year did what you are planning on doing,except i went about it a litle differently then chad.I rounded up the really weed infested areas and then waited 2 weeks,and really scalped that area with my mower.I then raked up any excess dead stuff and proceded to core aerorate the whole yard.. I then seeded the whole yard ,lying down extra seed where i had used the round-up.then i watered and the seed s would lodge into the holes and crevasses created by the aeration.I didnt begin all this till after labor day when the nights were a little cooler and the days still warm.I didnt notice much of a difference until the springtime but since then my yard has been thick and green throughout the summer even tho it gets maybe too much sun and very little water from me now.I might hold off on the seeding the rounded up spots if i were you for a few more weeks as were still getting wicked heat right now,but as far as aeration.you can do that anytime you want and the grass will benefit....good luck

Some say that slit seeding potentially gets more seeds into the soil than core aerating. In an ideal world, that is probably the case.
Practically speaking, you first need to determine which kind of slit seeder is available for rent, and logistically, how you can travel to rent it, do the job and return it in the proscribed period.
I found that the manually propelled slit seeders available at the local rental place (a Bluebird) as well as the model at Home Depot ( A Claussen) were way to difficult to push over an acre of ground which has some slight slopes. The model I rented at HD chewed up the ground too much and was a veritable contraption, even though it was almost brand new. The HD rental agent told me almost nobody ever rents that thing. I used that line back on him when I returned it early, and he gave me my money back. I used that to purchase a tow behind core aerator there.
I am sure that sod places probably have expensive slit seeders that are power driven and do not have a hopper of grass seed sitting precariously on top. If you can find a good slit seeder, that would be one way to do it.
If you have a lawn tractor and have a 1/2 acre or larger lot, the best and easiest way to overseed is to purchase a tow behind core aerator and do it yourself. You can run over the ground as many times as you want to, so you can get very good soil contact when you broadcast seed and starter fertilizer. If you pay for the core aeration, I would tell the contractor to double or triple the usual amount of passes/holes in contemplation for
overseeding. Cut the lawn very short before the core aeration. I had tremendous results with Lesco starter fertilizer which you can get at Home Depot. Get the seed where you think you will want to shop again for it next time you do this.