How often should I shampoo my hair?

I have thick curly hair and I wash it every night with Tresemme Flawless Curls shampoo and I use Tresemme Flawless Curls conditioner about 3 times a week. The only styling products I put in it are Aveda Light Elements Smoothing Fluid and Frizz-Ease Dream Curl Curl Perfecting Spray and I put those in everyday after I wash my hair. But I heard its bad to wash your hair ever day so how often should I wash mine?