It varies from women to women. Some of my girlfrens had their menses the very next month after giving birth despite totally breastfeeding the baby. General rule, the more you nurse the baby, especially during the first 6months, when baby is on total breastfeeding, mensus will be delayed -again there are exceptions . So sorry, no hard and fast gauage.
For me, I have not stopped breastfeeding since more than 4 years ago, and my mensus returned around 11-13 months after the birth of each child.