You can do it either way...... as long as you do it. Between warm up, staging lanes, burnout, making a pass, and returning to the trailer, I use about a gallon and a half. If you are bracket racing and going rounds you can go through several 5 gallon jugs in a hurry.
I just found it easier to bring the top lube with me when I picked up a drum of alcohol. I dumped it in there and by the time I was home it was totally mixed in.