Laundry?

Teri • wife...mother...stepmon...business owner... trying to stay sane while doing it all!
Curious as to how long I continue using dreft for baby, when will it be OK to use regular detergent clear and free of course? Also should I continue to wash her new clothes before she wears them for the first time. I did pre wash her clothes before I had her but new things as I buy them should I still prewash them??