Before training, taking creatine helps increase creatine levels in the muscles, thereby increasing muscular power during exercise.
After training, taking creatine can help replenish reserves depleted during exercise, and promote muscle recovery.
Creatine can be taken at a regular time of day, simply to maintain stable creatine levels in your muscles.
So there's no best time to take creatine, just make sure you maintain a regular level and stick to the recommended doses.