I had a phone call from a cousin in Sydeny last night who used it 2 weeks ago with her 2nd bubs.
She was one day overdue when she took it, already 2cm dialated for a few days since her internal at 40weeks.
She took 1T (as told by pharmacist) at 1pm and at 5.00pm had to go to the toilet (she was on there for 30 mins straight, very painful contractions started with the bowel motions) She said she was literally stuck on the toilet, between the cramps of bowel action, and the contraction. She thought she'd never stop going "number 2's", But just about 5.30 she stopped going. So then she called the hospital they said to come in. (She didn't have to use her bowels again for the whole time).
She ended up having really hard, fast contractions, and with no pain relief had bubs at 10.30pm that night.
So all up from the time contractions started (about 5.15pm it was only 5 or so hours.
I am almost 39 weeks pregnant with my 3rd, and as much as I want bubs now, I think I'm too much of a scardy cat to try Castor Oil.
But hope this helps hearing one experience.
Good Luck, but I think with Castor Oil your cervix has to pretty much be ripe, or already have started to dialate for it to work, so might need to wait until around your due date????
Mel, SA, Jayden 10/02, Harley 08/04, Zoe 09/06