I give birth 6 weeks ago how long will it take till my first period?

If you are breastfeeding, your period may not return until you start to wean, offer a bottle, or baby starts to skip a feed here or there (It could happen before that time as well however).
If you are formula feeding, usually about 6-8 weeks you will likely have a period return. It may be sporadic for a few cycles, or regular right from the start. Do use some type of birth control as you will ovulate before you have a period.