Naomi, are you bfing? You can get pg before AF arrives, as you can o first, then have your AF. If you are exclusively bfing (ie no formula or solids) and are feeding through the night, bfing is considered 98% effective as a conatraceptive for the first 6 months.

You can start to take the pill if you are not bfing (or mini-pill if you are bfing) 6 weeks after the birth and you do not need to wait for AF.