HAW! Here's another thing I know somethin' about. It takes me about a half hour to forty minutes to change strings, by the time I stretch the crap outta each one and retuning between stretches until they don't lose tune anymore. It takes longer to change but the strings stay in tune much longer.
As to how much to add before you make the fatal bend at the peg, I discovered a natural string guage on my own hand. I attach the string at the bridge and lay it up over the post and add the distance of the first two segments of my ring finger from the post to the point of the bend. Gives me about three and a half wraps around the post every time.
I got a telecaster with the old style tuning posts that you insert the wire in the center of the post and for that I use the whole length of the ring finger to allow for the extra inch that goes in the post.