I also haven't heard of the magic 12 week marker, but I would not worry about what other babies around you are doing, as difficult as it is not to compare they're all different.

Does it really bother YOU to rock her to sleep? Or is it more other peoples opinions of it? Because I got the third degree from friends and family who would cr@p on to me about 'making a rod for my back' rocking DD to sleep, but I know DD and she needed reassurance and her mummy when falling to sleep. She grew out of it on her own, and now nods off in bed without a problem.

I personally would do whatever works to make bedtime and naptime stress free, if she goes down easier feeding to sleep/rocking to sleep I'd do it. It won't be forever.

However if it does bother you to do it, I recommend the no cry sleep solution book by Elizabeth Pantley. It's full of great tips to help you baby sleep better and longer.

Good luck!