*this is an article I found these are not my words*
Many people find that after a few weeks, the gains they make on creatine monohydrate begin to taper off or even disappear altogether. There's an increasing belief among hardcore trainers that cycling creatine intake may help one experience continued progress with this proven supplement. Here's a typical creatine cycle you might try adding to your supplement program:
Week 1: load (20 g / day)
Week 2-4 : maintenance (10 g / day)
Week 5: load (20 g / day)
Week 6-8: OFF
Repeat Cycle
You're basically "on" for 5 weeks (higher than average doses), then "off" completely for 3 weeks. This seems to work well and can help give you continual progress with creatine supplementation.
Of course, another important factor is what type of creatine you're using. I never made great gains with creatine until I switched to a creatine formula as opposed to just mixing the powder up myself.