nipati …when he falls asleep/sleeps/is sleeping
…if she falls asleep/sleeps/is sleeping

These forms are used for unrealized events, when you want to say that something must happen before something else can happen. It is often found with another verb in the future.

Apu tshe minumatshiu mishta-mitshishuti.
She will not feel good if she eats too much.

These forms can also combine with other preverbs, like the completion preverb tshishi or the volitional preverb ui.

Tshishi-mitshishuti ekue tshe minumatshiut.
When she has finished eating, then she will feel better.

or a subordinate clause in the future:

Mishta-mitshisuti, apu tshe minumatshiut.
If he tries to eats too much, he will not feel good.

Initial change is not used with this conjugation.

Link to the conjugation guide.