So is it safer to wean them earlier than later?

I was afraid if weaning early will deprive them from getting the milk from mom that they might need. So I weaned my first couple litters at between 80-100 grams( I forgot to mark the dates so I don't have the age, I guess around 5-6 wks). Is that too late?

I just couldn't imagine they can get pregnant while that small.

If I lose track of the age, can I go with 250g as a guideline for starting to breed? The male can be any size from 250g and up, right?

Thanks.