I like your groups. I would maybe slide Dji to PG. It's way early, and things could obviously change, but if I separated by depth chart, I would maybe go:
Quinn
Grace
Walz
1 or 2 on the floor together, but not 3. Quinn and Walz likely not on floor together.
Burton
Crabtree/Bigelow
Noyes
Would probably rarely see 3 on the floor together, but certainly could happen at times. Mostly 1 or 2.
Goose
Roche
Randolph
Dread
1 or 2 on the floor together.
Nelson
Dji
Probably just one out there most of the time. Could see some minutes with both out there though, especially late with leads to have the most ball handlers out there. Hopefully, they both knock down FTs because you need your PGs to do that when protecting leads.
Nelson, being a PG, will play. The other young guys, it's just too hard to predict right now. If Noyes, Randolph, Dread, and Walz show enough to be part of the rotation, that makes us that much better. But, if not, let's not forgot they are mostly freshman (Randolph being the lone sophomore) this year, so they have plenty of time.