Rocco crawling and sitting

Rocco has begun to crawl. Well push up on all fours, rocking and shifting his knees. It's a matter if time, before he's full crWling. Last Friday he began to push/roll himself into a sitting position. He went full throttle info sitting alone, rolling into sitting and ready to crawl! He also rolls himself across rooms!!! His 7 mon check up has him off the charts at 24.4lbs and 31 inches!