they go at their own pace but tummy time help alot. my daughter started rolling front to back at 4 month and back to front at 5 months. just keep working on it!

3 in ah a half months is when my daughter first rolled over and at 4 months is when she would do it ALL the time Lol

my daughter was rolling on her side at about 2 1/2 months and fully rolling about 4ish