It was really fast when I did it. It may have taken 5 minutes at most.
It is super easy to do and loading up buttons is painless. I will make a suggestion and it is something I literally will NOT use the controller without...
I usually set my buttons up on multiple pages. I have a general rapid fire(Red LED), a slow rapid fire(Blue LED), a macro(Yellow LED), a sniper(Pink LED), and the last page is blank with the exception of a "page left" on a tac switch. I use a green LED on the last page to make it appear like a normal controller. That way, when I look down and see what appears to be a normal controller, I know that I am using a basic controller.
I am one of the few people who doesn't use rapid fire unless the other team is using rapid fire.