Promoting when you want shouldn't be an issue in SFI.
It's not even that big of a deal in the SFIII, you can jump to promotion class at level 10, and go to innovator class at level 20, or go all out for the better 17 then 30 in that game. This is because leveling in SFIII is horrible for the remainder of the levels, 18 through 20 for the base class, and 31 through 99 for both of the promotion and innovator classes, as getting actual stat increases for these levels requires in most cases constant resetting.
There is one character in SFIII however, that has all of his leveling completely backwards, where reaching level 30 before innovator class should be done, if the player plans to use him.
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