Anything spicy from being able to cast 6th level spells early?

[ATHATH]

One option is to take the apprentice feat and work with your DM to find an appropriate mentor.

Yeah, but then I can't grab Mastery of Day and Night before lv. 9.
I ideally want my feat progression to look like:
1: Least Dragonmark (Healing)
3: Maximize Spell
6: Mastery of Day and Night (the lonely stoner seems to free his mind at night)

But because of the Heal rank requirement, I have to instead go:
1: Least Dragonmark (Healing)
Flaw: Feat that gives me Heal as a class skill (there are a handful here: https://forums.giantitp.com/showthre...6#post20885236)
Flaw: Breath shenanigans feat (if I'm taking flaws, I might as well)
3: Maximize Spell
6: Mastery of Day and Night (the lonely stoner seems to free his mind at night)

Or, if flaws are banned, wait until level 9, by which point the damage will have fallen off.

EDIT: I checked Troacctid's big sheet, and there aren't any PrCs that this build can qualify for without investing feats that both A. progress invocations at lv. 1 and B. have Heal as a class skill. Sad!