Usually a couple days. Personally when it starts I try to remove everything from the area, maybe a lotion would help, but I find it's better for me to let it breathe naturally, rinsing occasionally to make sure it's clean. Personally I break out when I wear things continuously that were washed with cheaper/dyed detergents. Switch to free and clear detergents (I like the sheets, why pay for pods or liquids when you have water at home), and haven't broken out since.

Watch out, I also get it from some scented hand soaps and other items. If you notice it just stop use, and note that you should probably avoid those going forward