I breed both mice and rats.

The problem with mice is that they have a stronger smell and are hard to get started which is why many people tend to prefer rats, that and also the size, most people prefer feeding one larger prey compare to feeding several smaller ones.

What’s important with mice is security, if mice do not feel secure they will be stressed and be more likely to cannibalize their youngs (this is why I have mine in low dark tubs which provide plenty of security.
Other important element is quality food, not pet store junk.

When starting a colony you need to be patient first attempts might be failures if you are persistent and once you breeding project takes off it is a smooth ride as enjoyable as rats.

Best would be to start with 1.2.

Gestation is 21-23 days

Female usually give birth to 6 to 12 babies (that’s an average (my female produce between 10 to 18 babies each)
Mice can be weaned at 3 to 4 weeks.

Females can get pregnant again within hours of giving birth therefore your female can have babies every 3 weeks.

After 5 to 6 litter production start slowing down which is usually when I personally retire mine.