Hi,
The progressive uniform activation is independent from character statistics and can be started early or later.
There is a base EXH stat which is necessary to start activities with the clothing kits. There's also a maximum EXH stat which is required to have the final uniform unlocked.
It is not necessary to revert to an earlier game as lined out above the introduction of the uniforms can be started at any point. There is no risk for soft locking or locking yourself out.
progression from one uniform to the next level only takes three days max.It is necessary for the uniform to be actually worn for progression to occur.
y.v.
PS: my game is not compatible with any third-party mods at this point in time. Your save game states will be most likely corrupted if you have used a third-party mod or started the game with one.