If you are like me, you never spool your entire reel up with flourocarbon or braid. Heck, the stuff is just too expensive to do that with it. Also, if you are using braid, no mono backing will cause your braid to slip on your spool which will mean many lost fish.
So, ok, we use mono backing on our spools. How do you know how much to put on? Do you just fill it up to a certain point and then tie your braid/flouro to your backing and fill it the rest of the way? I suppose you could do that if you are familiar with your spool and how much line it holds.
I've got a few new reels over the last year that I am not very familiar with how much line they hold or where to stop spooling up my backing before I switch to my main line. So what I have been doing is filling up my reel with cheap mono. I fill it up all the way, just as if I were going fishing with that mono. Then I go to my front yard, tie on a heavy bait or weight and then give it a cast - a far cast - as far as I can cast. After I cast it, I then strip off about 25 - 50 foot more line. At that point I tie a small knot in my line right next to the spool. I then crank it all back in, go back inside and peel off line until I get to the knot I tied. I cut my line there and tie in my braid/flouro to my backing and fill my spool back up with my good line.
This seems to work fine for me. It gives me enough line for good long casts and plenty of extra line to offset for retieing and cutting off nicked/abraded line so that I don't run down to my knot any time soon.
What methods does everyone else use?