While on depo what time is the best time to try to get pregnant?

You almost cannot get pregnant during your period.

The human menstrual cycle is nominally four weeks. Starting with the first day of your period, normally you will become fertile on about day 14. Your fertile period thus is at exactly the opposite end of your cycle from when you are menstruating.

This does not mean that you cannot get pregnant from having sexual intercourse during your period. Normally, menstruation is 14 days after the start of your fertile period. If you have a short cycle, say 22 days, and your period is the first four days of that, and you have sex on day 4 of your period, when your fertile time starts on day 8 it will be only four days since you had sex. Sperm can live up to 6 days, and so it is possible that you will become pregnant.