Most salons and home dying product manufacturers recommend waiting four to six weeks between any major changes to your hair, including highlights and perms. The reason for this is because excessive dying or perming can damage your hair. Also, this time frame reflects the general time it takes for "roots to show."
Wait Less Than Four Weeks
If you want to change your hair colour more often then every four to six weeks, you will need to also do a deep conditioning treatment. These treatments put moisture back into your hair, and can prevent damage caused by excessive dying and perming.
It's best to wait at least four to six weeks between highlights. This will give your hair time to grow out and rejuvenate. While a deep conditioning helps with excessive dying, it is not a guarantee. Everybody's hair is different, so what may work for one person may not work for the next.