I am setting up my first group game and find myself wondering things like: How much interest is enough? Should I open a new thread for character recruitment? Is my plot comprehensible?
Are there resources for new GMs on elliquiy? May I ask those kinds of questions here?
If it's your first group game, don't expect it to run perfectly. You will make mistakes, as I made a ton when I first started doing groups. So much that I'm surprised some of them even got into the posting phase.
As far as gauging interest, and knowing when to start, consider the plot/story/game you have in mind, then decide how many characters you need to make it run smoothly. Don't start without everything you need, and at the same time, don't wait around for a ton of players, because people will likely lose interest if they aren't doing anything for extended periods of time.
But the best overall advice I can give you is make a set of rules, and stick with them
. Period. If a rule or concept has to be changed, and it's well into the game, poll your players for their thoughts and see if it agrees with everybody, or at least most of them.
If you have any specific questions, I'm GMing a moderately successful big group game, so I'd be happy to answer any specific questions via PM.