weaning at 25 days?

That sounds a little early to me, but that's what the manual I have suggests.  Is that the correct date?

Weaning as in starting solids, yes. Weaning as in not nursing anymore, no, definitely too young.

I do start orphans on solids around 3 weeks of age. . .but when kittens are with their mothers, it's a much more gradual and natural process. She'll take care of most everything. They'll eventually start eating from their mother's dish, then you'll know to give them their own plate of food. Be sure to introduce the litterbox when they start eating solids, as their mama won't want to clean them up anymore. Don't force or rush anything, it'll all come naturally. All you do is make sure the food is there .