Castor oil

I took castor oil almost 1.5 hrs ago.

First time I took it I threw up a minute later

This time I didn’t throw up

I’ve been having mild cramps on and off

No sign of pooping , very constipated

Having the cramping in my butt mostly and sharp pains in my vagina

I know it will only work if the baby is ready, but how long does it usually take if the baby IS ready?