Braxton hicks to contractions....?

Danielle • 33yo, first time mom and so excited for it all!! Married 10.03.2014 and we are over the moon about our Nov baby boy!
Any ladies have a good description of when Braxton hicks start to transform into real contractions? ..... I'm 35 weeks and 4 days and have BH constantly! Lots of pressure in my pelvis area too. Dr will check my cervix next week at my appt.