Every baby is different. But I think the average is 18 months.

@meganblevins, when you find out please share. He gives me 3 hours initially then every 2 hours after. Im exclusively breastfeeding. At night I would give him a bath, and warm pumped milk and he goes down 9:45-10 every night. But wish he can sleep at least 5 hours straight without getting up. When he wakes for the breast he goes down right away. So that's not bad. But I'm tired from waking every 2 hours.