What's the longest a male should be kept in with the females?

A bit older topic but...
I take male mouse away when the female's pregnancy starts to show properly, or few days before she's due giving birth :)
I let female's have 1 month break after every litter (i count 1 month after babies are weaned).
Also all females have max. 3 litters in their lifetime, usually just 2, because I don't breed females after they are about 1 year old.
And i separate male babies from females at the age of 3,5 - 4 weeks.