I'm only 34 weeks and 1 day

So I had a doctors appointment yesterday at 9 o'clock in the morning and they checked my cervix and it was closed and strong, last night around 10 o'clock I started getting really bad cramps I thought they were Braxton Hicks but as the night continued they continued to progress so this morning I went to the hospital and they check my cervix and my cervix is 50% thinner and she could feel my babies head in my pelvis, I think it's amazing how in just 24hours things can change. Has anyone else expierenced this and if so how long befor you went into labor ?