It isn’t necessary to do a loading phase with creatine.
By taking just 3-5 grams of creatine per day (depending on your body weight), your muscle cells will eventually become saturated with the creatine and it will have its maximal effect. However, if you don’t want to wait a few weeks for the creatine to build up in your muscle, you can jump start the process by completing a short 5-7 day loading phase. Just realize that the larger dose needed to do this can increase risk of stomach upset.
If you choose to load, take around 20-25 grams of creatine each day for 5-7 days. After this loading period, you can reduce the dose of creatine to five grams for men and three grams for women. If you choose not to load, just stick to the lower dose each day and your muscle cells should become fully saturated within a few weeks.