Sonia has been attempting to roll from back to tummy in earnest since about 3.5 months (and would get really frustrated that she couldn’t). Initially she would succeed in getting most of her body over, but her left arm would remain pinned at her side. The morning after her 4 mo birthday, though, I found her completely on her tummy with both arms in front of her for the first time, and she has been a tummy sleeper ever since (although often prefers to sleep with her arm pinned anyway)!
Interestingly, once she could roll from back to tummy, she forgot how to roll from tummy to back! She had been doing that since before 3 months by putting her arm out straight in front of her and letting her head weight carry her over, but now she has been trying to push with her legs to get her body over her arm that gets pinned like a T-Rex at her side. A few times I tried to help her do it the old way, but she would have none of that!
Right at 20 weeks, she figured out how to get onto her back via her new method, and now no corner of the crib goes unexplored as she tosses and turns her way to sleep. We are so proud of our little roller! Of course it’s right on to the next milestone as she’s already making the motions to try to scoot and crawl 🙂