If you can wait until fall, and I realize you are anxious to get out there and tear stuff up, it is far better to seed in the fall. You can dethatch now if you think you have problems. Usually Kentucky bluegrass is the only grass that might have thatch problems. You can aerate any time.

You want thatch removed when it poses a problem to suffocating the soil beneath it. Air and moisture is important to get down to the soil and feed the grass roots.

If you feel you wish to aerate then that can be done in spring and will remove thatch at the same time.
You want to use it when the soil has dried somewhat...you don't want to take a tractor over soppy ground..making impressions that take a long time to work their way out.

Seeding is done when the soil temperature is conducive to seed germination...so that is later in spring...if spring is your choice. There's never a wrong time to overseed....just some times are better to obtain good results. Spring seeding should never be put off until the fall if the lawn needs such fixing.
There is ample water in the ground at this time from snow and spring rains. So the time is ripe to overseed.
If you like, do the aerating, remove some the thatch, and then overseed. Whether you spread a thin layer of compost(topsoil) over the seeding is up to you. Some people layer 1/2" of compost over the lawn, then overseed. Either way is your choice.

The results that come from overseeding can depend on how you water it, the amount of sunlight and the temperature of the soil...(not the air temperature)
Seed too early, it will just sit...and wait until the optimum time. That's not a bad thing to do anyway...the lawn decides whether the seed germinates or not.
Or you can wait until the weather improves and the soil temperature warms up to invite germination.

Whether you use a "starter" fertilizer is up to you. Many recommend it. This fertilizer can make the resulting seed stronger, better able to stand up to what might be thrown at it. Some do not fertilize at the time of seeding; they wait rather until after the second mowing of the new grass before giving it food. Again, its up to you!

I was not familiar with the John Deere Thatcherator, so I had to look it up. Contrary to what you may have been led to believe--it does not aerate. It is designed to de-thatch. I have used another manufacture's version of the thatcherator and if you carefully adjust the weight, it can do a decent job of de-thatching a lawn.

Early spring and fall are the best times to de-thatch as long as the ground is firm enough to hold the tractor and in fall when there is enough growing season for the turf to heal itself as de-thatching is an agressive lawn care act. In the spring, de-thatching should be done prior to putting down pre-emergent or you are going to both bring up weed seed and break the pre-emergent barrier. Be prepared to follow up with a lot of raking and disposal what you pull up. If you are not using a pre-emergent, you can overseed in the spring after de-thatching as it does rough up the soil somewhat. (But it is recommended that overseeding be done in the fall for a number of reasons.) All in all, if you haven't used a pre-emergent, have at it with the de-thatching, overseeding and applying a starter fertilizer.