I haven't spooled with any flourocarbon yet, but when I do, I will fill my spool with a cheaper line that is is the same diameter or as close as possible to the flourocarbon that I will be using, make several casts with the heaviest best casting lure that is suitable for that particular rod. After a series of casts, I will pull off a little bit extra line, cut the cheap line, tie on the flourocarbon and fill up the spool with the flourocarbon.