When did your braxton hicks start in your pregnancies?

tell me about your experience of braxton hicks, i started getting them at about 6 or 7 months with my first child and at 15 weeks with my second, for me it is generally not painfull but more uncomfortable and happens all over the place but not frequently my stomache starts going stiff then hardens and pulls while it contracts for about 5 second it kind of up and then relaxes, the reason why i ask is that i noticed that not many will know that it is supposed to be normal to get them at any stage, so i would like to hear from pregnant women what there experiences are?