Mine can fluctuate a bit - mostly depending on how much I have been hydrating. I am at the beginning of stage 3 - and have been encouraged to drink lots of water to help flush my kidneys out. When I was first diagnosed, my creatine levels were in the 1.6-1.7 range. After adopting a serious 'stay hydrated' lifestyle, my creatine levels have been at the 1.23-1.3 levels.
I already eat a pretty kidney friendly diet (for my stage) so the biggest impact on creatine levels has been staying hydrated.
My nephrologist said that 24 hr urine collections give a better idea of kidney function than do blood tests because the creatine levels can fluctuate during the day due to factors such as dehydration. I keep this in mind and use as a reminder to hydrate