So how are people progressing with their projects?
Are people working on lore, story/quests, dialog, designing maps or in-game levels (as much as is possible now), or a mixture of any of those?
I never prepare stories, quests or dialoge as I like to run "player driven" campaigns. I just create a setting, set the players loose in it and take it from there.
I am designing maps and ingame levels and doing some test builds in the DOS1 editor.
This Friday the group will start playing Act1 in early access together to get a feel for the game, test party composition and tactics.
So yes preparations to start a campaign sept. 15th are in full swing

EDIT
Just had some bad news on steam though.
"Same level area transitions (as in from the first floor to the basement of a house) will probably not work"
Steam Discussion That most likely will change the nature of my campaign.
I will still try to run it as free form as I can, but I have this nagging feeling the tools will try to force me to run it as a series of encounters instead.