rotations only matter when you are able to use ALL your abilities. Meaning once you reach 50. If you miss a level 19 Ability in Sastasha while being 22 it doesn't matter.
You want to do cool 50 moves? Why not play as level 50? In Level 50 Content? And Unless you get ifrit as low level roulette. Nothing is worth the time for the few extra tomes you can get by other means faster.