According to my experience, I think hair mask works best when you put it on slightly dry or dry hair.
Deep Conditioner works best when you use it on squeezed-dry damp hair (sorry but don't know how to describe, basically you squeeze excess water out of your hair after shampooing). Don't let a lot of water on when you are applying conditioner, water dilutes the efficiency of deep conditioner.
Even better if you cover you hair with hot towel while conditioning.