Caffeine half-life is 4 hours.
If you're taking your creatine for the volumization properties of creatine, you shouldn't worry about timing. Caffeine has been shown to not affect muscle Cr uptake or the volumization effect of Cr.
If you're taking your creatine for strength, then you need to worry about timing and such. Give yourself at least the four hours, although I've never seen any papers that had the creatine and caffeine dosages administered at different times. I don't know if the strength benefits of"creatine would still be hindered, and I don't think anyone can really tell you for sure because it hasn't been stuided yet.