HI Jas,
I started using it at 40weeks. I wish I had have used it earlier as I know that it helped with ripening my cervix. I think you are safe to start uding it at around 38weks internally and from now I think it is safe to have it orally.

I used to insert 2 capsues in just before I went to sleep but make sure you wear a pad or something as it kind of leaks out (sorry for TMI).

After I started using it my cervix was 95% effaced within a week, so I think that helped. I went into labour 13days after using EPO. My labour was 7hours and it was my first child.