Creatine isn’t a wonder steroid, it’s just going to help you get a few more reps in. These extra reps should occur a day or two after taking it regularly. In fact it may be easy not to notice them unless you are measuring accurately how much you normally lift.
So depending on your regime and diet, imagine adding a few extra reps to your lifts and expect to see results based on that! So I would give it at least a month of good hard training before expecting dramatic results.
But considering the last reps are the most important, creatine can really help your strength training.
These guys did a video of their results with our creatine, it only took them three weeks to put a half an inch onto their arms:
https://www.youtube.com/watch?v=cahK5CuvBLM