I usually do 3 days in, 3 days out. Sometimes I will forget to put a male in and the girls will go 4-5 days without having a date, and on occasion I'll forget to take the male out or they will be in an extremely long lock and the male will stay in for 4 days. I don't really stick to a strict schedule, but next year I plan to really record every introduction and when I take the males out, record locks, etc.
As far as weight, I bred a male last season who was 550g. He got the job done even though the clutch ended up dying off. My minimum weight for males is 500g.