When I first started, I was lazy and just spooled the whole thing with whatever line I wanted. Then as I became more confident in knot tying, and realizing the innermost 2/3's of a spool will probably never see the light of day, I started to use backing.
I do a full spool of backing, then walk it out 75 yards, then cut it, then tie on my main line and spool it full again, depending on the rod/reel. I make sure I take it out far enough that when I re-spool, it covers the knot comfortably.
I walk it from my family room through the kitchen and back 4 times which is approximately 75 yards, or, in your case, you can pace off 50-55 steps, where each step is about 1 yard.