OK I hear you and let's go through this thoroughly so you are confident in what you are doing.
When staring a new lawn, or renovating an existing lawn with an overseeding, you are temporarily departing from the normal best practices of how you traditionally maintain a lawn. As soon as the renovation is up and growing, you slowly go back to your old practices.
1) Aeration should occur only when the grass is actively growing -- in Fall (late summer is usually OK in the north), or in Spring. So that means that the renovation should wait until then.
2) You can and will mow as soon as the existing lawn requires it, it does not have to do with when the new seedlings come up. Repeat -- You will not base your first mowing on the new seedlings. You will base it upon the existing lawn.
3) #2 helps explain why you scalp it down to 1", or 1-1/4" or 1-1/2". The shorter it is cut, the longer the seedlings have before they will be mowed over. It's not nearly the big deal you think it is to mow over new seedlings. They can take it. And, if some plants are weak and can't take the scalping, so be it. New seedlings will take their place from the overseed. But don't worry here, you aren't going to lose your lawn.
4) Fall germination is ideal because of warm soil temperatures, thus the germination is the fastest it can practically be. Technically right now is when germination would occur the fastest (hotest soil temperature). But keeping the seeds moist is impossible and once they dry out, they die. Point is, you'll be pleasantly surprised how fast it begins germinating. My guess is you will see new grass plants sprouting in 10-14 days, with all of it up in 4-5 weeks.
5) Your watering practices are going to be altered during this time. You do not want lots of water on the lawn during the first 2-3 weeks. Why? Because a flooding rain, or a drenching watering with a sprinkler or hose risks the seeds washing away, or almost as bad, bunching up in the low spots of the yard while other areas wash away bare. Learn this lesson the easy way -- if a heavy rain is predicited in the next several days, WAIT. It can destroy your hard work. Ideally you get NO RAIN, so that you can fully control the watering.
6) You water 1 or 2 times a day as needed. Sometimes depending upon conditions, it's one very light watering a day is enough. You have to actually monitor it yourself, and watch for areas that are in the heavy sun versus the shade. Keep everything MOIST, not soaked.
7) Do not water deeply in these first few weeks. The light watering you are doing is enough to keep all the existing grass going. Now, does that scalping and shallow watering hurt the existing lawn? No. What is does is reduce the depth of the roots. Now that sounds bad, which it is, but remember -- the goal here is to renovate the entire lawn.
8) After the germination begins, continue watering lightly the same way for about 2 more weeks, enough time for all the seeds to germinate. Then, begin to water once every 2 days, 3 days, until you are back at your normal watering schedule. The 1" rule can go back in effect at about 4 weeks or so, and if after the first 2 weeks you get a heavy rain, it will probably be OK.
9) Mowing -- you scalp it once. After that, go back to mowing at your ideal Fall height, somewhere around 2-1/2" or so. Mow as soon as it needs it (say 2-3 weeks), then mow it again as often as necessary. No hard, sharp turns, be gentle on the new lawn. The new seedlings have no input in when the mowing is done.
10) About 4-6 weeks after you overseed, you should be back at your normal schedule again. The roots will begin to grow deeper, the new seeds are coming in and you are now back to the traditional lawn maintenance plan you usually follow.
I've done this many times, and usually do it every Fall. I've read and discussed all these issues with many of the folks here and am confident I do this correctly.