I think the app is really iffy. We booked just before 90 days out. Last month I was able to book all of our dining reservations; 7:00 p.m. each night in the same MDR other than 2 specialty dinners which I was able to also book (we have the premier pkg). These reservations do show up on the app on my phone.
A couple of weeks ago I was able to access the full ship itinerary including activities and such. Luckily I notated days/events that I want to remember; 70's night, formal nights, M&G mtg, etc. Now it would seem that the only info I can find on the app is port dates.
As I said....iffy at best !!