My advice (since I made mine at the end of April)...
I'm assuming you are already registered on the WDW website and that you have attached your reservation to your registration. If not, make sure you do that.
If you're staying onsite and trying to do the 180+10, make sure that you watch the date when you start. Mine was defaulting to the current date and it took me a couple minutes to realize that I needed to change the date to my check-in date. I would have thought that it would have the check-in date loaded since I said that I wanted to make reservations for that trip, but it doesn't.
If you have a time in mind, put that time in for the ADR that you want. Don't choose "dinner", because it won't necessarily give you options for the time that you think of as dinner. For example, I was making a dinner ADR and I chose "dinner", thinking it would give me all the time options. Nope, it only gave me 2 or 3 and I think one was at 7:40 and the other was 9:10, or something like that. I wanted around 6pm. When I put in 6pm, it gave me plenty of options around that time.
Hope this info helps! Once I figured it out, the online ADR's were smooth sailing and I got everything I wanted at the times I wanted.