They start at 6 weeks you can feel them any time after then
Braxton hicks are practice contractions. Getting your body ready for the real deal. You may start to feel them around 20 weeks usually. Your tummy feels hard it usually does not hurt just uncomfortable for about 30 second. I get them all the time. If you feel contractions that only are getting more frequent and more painful they are usually real contractions. Depending on how far along you are your doc might admit you or give you something to stop the contractions and send you home.