Preparation for Recoloring Leather Seats

I sanded all areas of a currently black leather bucket seat in preparation for recoloring them to a mid-brown. I only scuffed the leather to give the new paint some tooth. I did not attempt to go completely through the black color. The leather appears to be stiff, probably due to its age, 1972 vintage. I am using Surflex from Color Plus.

Should I apply the leather softener before I apply the new color, or after?