Yeah, Si is. He rolled and pushed himself up at 2 weeks - though I think that was an accident from having such an arched back from wind - all that arching and wriggling made him pretty strong. We probably figured the tummy thing out a little later than 3 weeks, maybe 8weeks when he started sleeping through, and how that happened was that we'd start him on his back, and then when he woke, we flipped him to his tummy. Wasn't long before dh just started him off on his tummy in the first place.

You know all the other SIDS recommendations though, so you can still keep those. Nothing that could cover his face, no toys in cot, nice firm mattress, good airflow in room. Don't wrap him either, at least not his arms. Make sure he won't overheat, I've heard that's the main issue with tummy sleeping - my MCHN said that when I was little (my generation were mostly tummy slept) there wasn't too much central heating around, so bedrooms and babies tended to stay a bit cooler.