My boy shows no signs of crawling back then n one morning i was out of the room for less than 5mins n he is at the other end of the room already when i returned. Got a great shock! When he started crawling he prefers to go all flat on the floor n crawl like those army style. Think they called it the leopard crawl or something? Even when he had known how to crawl on fours he still prefers to go flat.
Let him b on the ground as often as you can. Just b patience. Sometimes they know you r eager to c so they purposely dont wanna do.