Hi Luey, My first pregnancy I didn't use anything and got no stretch marks (however I did give birth at 28.6 weeks). This pregnancy I've used the Palmers Stretch mark cream since the start and didn't get any until around 30 weeks and have now got three red ones on my tummy and a fair few around my hips. So I stopped using the Palmers and started on the Bio Oil. To tell you the truth I don't think they do much, I've you're going to get stretch marks you'll get them, but the Bio Oil is good, I'd suggest anything with vitamin E. I had a huge scar on my arm from falling off a horse and applied pure Vitamin E from a capsule onto it and the scar healed really well.
Goodluck with it!