My girlfriend and I would like to get married after getting a K-1 visa and bringing her to the U.S..(continued

I'm a U.S. citizen, she's from the Czech Republic. We want to apply for the K-1 visa (fiance visa) now since it takes 6 months to get, and I'm going to Czech where she lives while we wait for it. Once she gets it, how long can she stay in Czech with the K-1 visa before she has to come over to the U.S. and start the countdown of the 90 days?? because we'd probably get it around next February 09 but we don't want to come to the U.S. till July 09. Any help would be huge for us. Thanks.