My firstborn did this at 2 weeks old but it wasn't an intentional movement until much later.
My daughter did it for the first time when she was super little as well. But then it didn't happen again until she was about 3 months old. Usually in the beginning it is just an accident.
both of mine were over 5 months before they rolled. Interestingly, my second was sitting steady by 3 1/2 months though. Once they sit, I forget about tummy time (oops). My first also sat relatively early, although not as early (5 months). Some of my friend's babies started to roll a week after birth. Point of all of this is- don't worry about it! Mine rolled really late, but were early or on time for other big milestones.
with my son (whos 7 now ) he never rolled over at 1 he just started walk (he didn't crawl either. My daughter who is 8 months rolled over at 7 months and sat up at 7 too.
hehe, like I said some kids discover it on accident sooner...but he won't have the muscles to repeat this in a controlled (or intentional) manner for quite sometime. He may repeat it but it's generally just a "wow, what did I just do?" instead of "I'm going to roll over now".
My son is only 3 weeks old. and he was layin on his back crying for a bottle and rolled on to his stomach
my guys started rolling around 2 1/2 months. after that i couldn't keep them off their belly.
From babycenter.com:
At about 3 months, when placed on his stomach, your baby will lift his head and shoulders high, using his arms for support. This mini-pushup helps him strengthen the muscles he'll use to roll over. He'll amaze you (and himself!) the first time he flips over. (While babies often flip from front to back first, doing it the other way is perfectly normal, too.)
At 5 months your baby will probably be able to lift his head, push up on his arms, and arch his back to lift his chest off the ground. He may even rock on his stomach, kick his legs, and swim with his arms. All these exercises help him develop the muscles he needs to roll over in both directions — likely by the time he's about 6 months old.
My son is 4 months old and has rolled both ways (from stomach to his back first and from his back to his stomach later)....but he still doesn't do it consistently....but he tries soooo hard to do it all of the time ;-) He rolled from his stomach to his back for the first time when he was 3.5 months old. I looked back in my older son's baby book, and he did it about that same time, too. If they do it any sooner than that, it's likely just a fluky thing.
generally around 2 months (8wks) but some babies accidentally discover the ability sooner. Remember not to go by the milestones exactly. some babies develop physically VERY fast and slower when it comes to speech or emotional development, some babies are early speakers/cooers but take longer to sit up and roll over. some babies develop both things faster, some slower....and it's just a guideline. so when they say "a baby should learn to roll over at about 2 months", they really mean any time from 6wks-12wks is normal. the key is not to expect baby to "meet" the milestones, but make sure that if they get a month or so past the milestone mark you talk to the pediatrician.