How many months did your baby start crawling ?

My nephew started crawling at 8 months while my niece started when she is just past 6 months. My niece is younger than my nephew and appeared to be achieving all her developmental milestones slightly earlier than average. Typically, a baby would start crawling at around 7 to 9 months. Usually soon after he/she is able to push his/her chest off the ground while on tummy time and subsequently onto his/her arms and knees. I've heard of babies who "bypassed" crawling and went straight to standing and walking. It's really fun to see how they develop and the joy on their faces when they took their first "steps". ;)