Hey there. I'm not an expert by any means, so perhaps I'm wrong here. But I MCed the first session of my first AW game this past Tuesday and so had out the 1st Session Sheet. The way I did things was thusly.
I used the notes and reminders on the 1st Session Sheet as a play aid. It's got the Agenda, Principles, and MC Moves on it, along with a nice list of NPC names, and the things to do during the 1st session. I wrote the PC's names and what Playbook they were in the center circle, but that was it. I scribbled all my other notes onto scratch paper because frankly, my handwriting sucks.
Now that the session is over, I've been looking at my notes and trying to fit the pieces together. When I decide what the Threats actually are and have determined their types, cast, resources, and some "I wonder..." questions, I'll write them down on the sheet. I'm pretty sure that the 1st Session Sheet then becomes the home front. So I would assume that you'll use the 1st Session Sheet in every session from now on, until or unless the players move to a new home front, or the situation changes so significantly that the home front needs to be reset from zero again.
Like, I don't see any reason why you couldn't use a "real" Fronts sheet for the home front. But there are some things on the 1st Session Sheet that are more general and apply to running the game, as opposed to the specialized Fronts sheets which are pretty much only for a single, specific front. Does that make any sense?