Drain battery before swapping?

I am going to change my lithium battery on mid-2012 Mac book pro. Some websites suggest draining the battery for safety reasons. Some instructions also recommend that I shut down the computer all the way before changing the battery. I am trying to think about how I could accomplish both or these things. If I leave it on it will drain but the OS wasn’t put to sleep properly, whereas if I put the computer to sleep it won’t drain the battery. I have a flash drive so maybe it doesn’t matter, and I can just drain the battery to death before the repair.