I understand AADSAS generally opens the new application  in early June. Should I wait for summer grades and apply on August 1st, or should I just go ahead and apply early [assuming I'm a weaker candidate].
I will be taking the DAT in late January and potentially in May if needed. Practice exams are placing me around 20/21. My recent grades have been high, however due to early college I'm going to be applying around ~3.3cgpa and ~3.25sgpa
I would definitely apply early in June rather than August. You can always update your summer grades during the Academic Update period in November or you can call each school and ask them if you can send your summer transcript directly to their office instead of waiting for the Academic Update.