Heard back from keratin4u:

"You should color your hair first than you can wash with the clarifying shampoo and than apply the treatment.
I did the same thing. I did the treatment in the afternoon than only washed the hair the next morning. before you wash the hair just falt iron again a bit."

I did the treatment yesterday, am about to wash it out now. It did make my eyes water a little, but otherwise, it smelled like white chocolate and I didn't have any problems.