Colby used to like tummy time but never did much moving! He was quite happy to lie there and watch. Then one day he just started rolling everywhere! He would roll instead of crawling until he was about 7 mths old. He then progressed to comando crawl and just in the last couple of weeks he has gone to "proper" crawl and cruising the furniture (and walls!) He will now walk beside us holding one hand and can stand on his own for a second...until he realises he's not holding on! I believe that swimming lessons have helped Colby's gross motor development.
Colby started to get into a lying position from sitting and sitting position from lying down when he was about 8 mths but all babies develop differently.
My point after all this blah, blah, blah!!!! is that some babies seem to be doing nothing much but once they start moving about they can develop pretty quickly and catch up to their peers.
Kym - Mum to Jada (27.09.01) & Colby (21.01.04)