I don't have any advice but I am in the same boat!! My pediatrician told me that some babies don't crawl and will just start walking so I'm thinking/hoping that's why he's not crawling yet!
Crawling may occur anywhere from 6-12 months. Or be skipped entirely as mentioned above. Or may be replaced by scooching around. My niece only crawled at 10 months despite showing lots of eagerness to do so. My LO shows no desire at 6 1/2 months now, but likes sitting and scooches around a little. No worries, as each baby develops at his or her own pace! Try to continue lots of tummy time, play with your LO lots, and try not to be too concerned.
Re: Crawl