It depends on the country you are in and the MW, doc you see. Most MWs don't offer them in UK untill you are over 41 weeks. Personally I think its a bit daft to offer them before you are overdue. There are not huge risks involved but it is an intervention after all (and as with any intevention there are drawbacks), so why do it so early if there in no medical reason? If you are not close to being ready it will just tend to make you loose sleep because of being crampy and uncomfortable or getting excited because of contractions, bleeding, or lost mucus plug that turns out to be nothing. If it works it works fairly quickly so worth a try to get things kick started a day or two before trying other methods of induction. That's just my personal oppinion some ladies think its worth a try earlier.