Don't take Castor Oil, it can cause baby to have a bowel movement in the womb and can be fatal to him/her.
My doctor checked me at 36 weeks but never again after that because she didn't think it would change much. I went into labor at 38+3 weeks! ask them to check you
You can ask your dr to check! Some dont like to stir up a trouble by this procedure. So you should ask or do a self check, see if cervix passes a finger tip or two. That will give you an idea if you progress or not. My dr did not recommend castor oil under any circumstances, it gives complications in dome cases.
I am 40 weeks and my doctor hasnt checked me either. I think it just depends on your doctor /: