It's not a safe assumption - there are many things that can happen that will keep them from opening the attraction to guests during test and adjust sessions. All it takes is one centrifuge breaking down, and they'll quickly close the line because 40 guests every 6:45 minutes simply isn't cutting it. And these breakdowns still happen frequently.
Chances are that they will probably try to open it after 4 pm. Good luck - it's an awesome ride!