It only takes about 20 minutes to get the first dose of antibiotics in so I would say yes to your question. That said most Drs don't think it is necessary to give the antibiotics for gbs if you are having a c section. You should ask your Dr what his protocol is for administering antibiotics. Gbs resides in the lower third of the vagina and exposure to the baby generally takes place as it travels through the birth canal. This is the reason most Dr give for not giving c section moms antibiotics.
Personally...I think if your water does break you should make sure to request the antibiotics...better safe than sorry I say.
