I'd say, if you're on park before 10.. join the queue then.
Unlike any new ride opening, the ride is just not getting quieter during the day. If anything, it gets busier particularly with school trips. Then at the end of the day, the queue gets even bigger as everyone else joins it.
Essentially, there just is no best time to visit. Go as early as possible, buy fastrack, use single riders imo. Don't bother with middle of day, you'll waste your time (I joined queue just after 2, it was my last ride the other week.)