Yea if you can't see your usage on the website the app won't work either from my experience. I couldn't see data usage when my account was new or at the beginning of a new billing month.
I'm at 915mb and I'm 22 days in. I usually stream an episode of a show during lunch via Netflix on the weekdays and I'll browse during the day. I kind of wish the cap was higher or gone, although to be honest it doesn't really affect how I use the phone.