On your main
MDE page (online, not the app), it will tell you how many days to go Disney thinks you have. On the website, click the MDE dropdown and click on your name. Left hand side about half way down it says - "My Plans - XXX days to go". It should say 181 today

. Tomorrow it will say 180 even before 11am, but it still won't let you book ADRs until that time.
It was one day out of what I'd calculated it to be when I did mine a couple of weeks ago, but that's probably me...
MDE was glitching a bit the day I did mine - had to log out and log in again a couple of times. Seemed to work better if I picked a date AND a time from the main dining page, rather than just "Dinner". If I picked a restaurant before searching for a time, it seemed to silently log me out. But despite not getting anything on until about 11.30am, I still managed to book everything pretty much exactly as I wanted it, although wanting BOG on the 180+9 day probably helped there.
Try not to get too stressed

, and good luck!
Oh, and +1 to the previous poster - get your card registered in advance. All goes very smoothly once you get going then - I did 9 reservations in 10 minutes or less.