It was about 3 weeks with DS2 (em c section after abruption, very painful recovery) but it was still painful so DH pushed him for another week or two.
With DD it was 2 weeks, only because we were in hospital for a week and then I didn't go anywhere except with DH and he pushed the pram.
Personally, I would wait 2 weeks. Not because of pushing the pram, but even though I recovered super quick with DD (I was driving after 2 weeks) I still got tired quite rapidly, so wouldn't want to go out for a walk feeling fine and then suddenly get tired or sore and have to walk back home. Or just don't go that far...
And also, awww, my DS1 is a Michael too