Runs should start with a blank file on slots 1, 2, and 3 as all files are used during the run.
It is helpful to watch a reference run when learning, as this route document can only go into so much detail. The top runs on the leaderboard use the optimal route, but these older runs follow this route:
(Note: Alternatively you can do the old route which doesn't use Poe 1 Skip. This is around 45 seconds slower if you get Poe 1 Skip first try.)