I am not a cue maker so that you know that right up front, but I have been doing leather work for the last few years making holsters, belts, and other items. when It comes to leather I would say to dye the leather first otherwise you could be making a big mess and getting it all over the butt of the cue, also if you know the type of leather and that it can be dyed easily then no problem, the best thing is to try a small section first to see how it takes the dye as it might take a few coats to get it to the desired color that you are looking for. Even the type of dye can have strange effects based one how much dye and if it has been thinned out. Some dyes have a great deal of pigment added to it and will have a strange outcome if not careful and would need to be thinned out with denatured alcohol before you actually dye the leather your going to use. Others may have a different answer than what I have given or you might already know some of what I just mentioned good luck with your project. Another point is that when most leather is dyed it has a tendency to dry out and harden so you then need to treat it to soften it back to a comfortable feeling that can be done several different ways.