It would be smart to get immortal approval BEFORE rolling if you plan to do something crazy like that. It's not something I'd recommend and it will test your patience for the reasons above AND because it's not something we like to hand out or encourage in the vast majority of cases.

It's tough because we have to enforce norms (would good-aligned high elves be normal if 1/3 who rolled wanted to become evil? would evil drow be normal if everyone could become Drizzt?). But we also want to encourage creativity and make sure everyone's having fun.

I think there is plenty of fun to be had within norms. If you're really dead set on doing something different, ie changing classes, races, alignments, whatever, expect it to take a lot of patience and expect never to be quite the same/as powerful as if you simply rolled that way.

tldr you need to be a masochist to do this.