When do most infants begin to crawl or creep?

Creeping (moving along on the stomach) occurs between 6 and 8 months of age - after a baby starts sitting up on her own. Babies may or may not move on to crawling (moving along on hands and knees), and some may start by crawling backward !

It is not important for a baby to crawl. If she goes directly from creeping to standing and walking, then that is OK, too.