I really doubt G+ will be sold out before 7am.
If they divide the G+ supply into 4 buckets, one for MK, EC, HS, and AK; no way those all get filled right away.
There could even be more buckets (8 total), those with park hoppers. But I doubt this is how it actually is, instead it's just 1 big ol bucket.
For my Christmas 2021 trip, I woke up daily around 6:40am. Got breakfast and bought G+. Then started making plans of what my first LL would be and headed for the parks. I just really don't see a reason to stay up until 12am to buy G+.