There are some guidelines they follow: announcements around when tickets go on sale, announcements during "down" times to keep engagement high, a full-court press the 45 days, etc. That doesn't mean they'll follow them (see 2017 and last year) but it's good for guessing. My gut says they'll follow something like 2017 where they sprinkle announcements throughout the year but mostly focus on late July/August.
Anyway, some interesting audition info:
auditions.universalorlando.com