Leave it up to the doctors. They know what they're checking for.
The first time i was checked when i was in active labour and was 4 cms. Doctors where i am from dont start checking until about 38 weeks. All that "checking" can stir things up and put you into labour. I wouldnt check myself. Also someone mentioned infection and who knows if you would do it right!
You should not check your own cervix,it risks infection and you dont know what your looking for,best to leave it to your doctor as they know what they are doin and will check you when its needed