Although eight weeks is the recommended time frame to go between relaxer touch-ups, some women simply can't seem to wait that long. Eight weeks is a general guideline, but the time between touch-ups needs to take into consideration two things: the length of your hair and how quickly your hair grows.
If you wear a short, tapered style, chances are the sides and back of your hair will need a touch-up before eight weeks to keep your look uniform and neat. In this case, if you trim your sides and back at the same time that you relax only these areas of your hair, you likely won't sustain any hair damage.
For short, tapered styles you may find that a touch-up every three or four weeks is needed to match the closely-cropped parts of your hairstyle to the longer crown area.
Hair grows an average of 1/2 inch per month, but some people report that their hair grows more quickly or more slowly than this. While most women will see 1 inch of new growth after eight weeks, what if your new growth is closer to 1 1/2 inch? You may want a touch-up after six weeks to maintain that straight, sleek style.