Yes, that's 6 am eastern, so 5 am for us in central. I did it about a week and a half ago. I wasn't online at exactly 5; I was still sleeping at exactly 5. I was started before 6, however.
Once you have something in your cart, you have it, so do your hardest to get ADRs first, but don't bother checking out yet. You can put up to 10 ADRs in your cart before you check out.
I will say, I got everything I wanted at exactly the time and day I requested. I was a little shocked. (Yes, that includes Le Cellier and CRT. We've never done Le Cellier before, but we were curious about it after reading all the, admittedly mixed, reviews here on the disboards.)
I really liked the online ADRs. The only complaint I have is that is requires that you pay in full for CRT, and we have a TiW card, which gives 20% off, and there is no place to put it on the website, so I didn't get my discount. I tried to call later and talk to a CM about it, but they said they would have to cancel and reschedule and there is a chance I could lose the reservation in those seconds.