It is very difficult to say when your periods will return as every woman is different and it will very much depend on how you are feeding your baby.
If you are exclusively breastfeeding this will delay the return of your periods for however long you breastfeed.
If you are supplementing with formula your periods could return anytime from 3 to 8 months after you start to supplement.
If you are formula feeding your period can return anywhere from 5 weeks to 3 Months after giving birth!!
If you are worried or concerned that your period has not returned discuss this with your GP.