By day 50, you should be able to see some pattern of the snake when candled with a bright light. If you already cut it, you should definately be able to see a snake in there, but day 50 is a bit earlyish to cut in my opinion. This was my first year of breeding, and I waited until day 60. It depends on you temps too; what temperature have you kept them at? Just be sure that if you do cut, you are not rupturing the clear membrane of the sac that the snake is in. If it is not ready to breathe air, this could kill it.