Seeing how others tackle the same problem is helping me to form ideas for my own work. I am in awe at what others have done. Makes me say, 'why didn't I think of that?'.

I don't think you're overthinking so much as over stressing about it. I suggest approaching it as play, especially since elsewhere you've mentioned feeling intimidated by the first 13. The challenge is an experiment; do the best you can, but ultimately it's a learning experience. You'll learn just from doing it and from looking at how others approach it. If what you write doesn't work well for you, you can always try again next week.

As for non-challenge first 13s, I rarely work them separately from the rest of the piece. Though I keep in mind that i want to entice the reader early on, I think that the first 13 needs to arise naturally and transition seamlessly into the rest of the story. That to me is more important than creating a "hooky" opening. Too much focus on the beginning makes it sound forced, in my opinion, or has such an intense beginning that the rest of the story fizzles out.

Edited to remove identifiable material! (I realized I posted something that might give me away in the challenge)

It's not about time.

A tough fact for me to learn was: Not everyone is the reader I'm writing for. Some people don't like the type of story or character I'm writing about--when I'm that reader, I don't comment--and nothing will make them like it.

Other than that, there are stages one goes through while learning to get something out of critiques:

1) What-the-****-are-you-blind? / You're-just-being-obtuse! Stage is usually first. It's seldom said, but often thought by the author. This is generally because you write what you see (and forget we can't see it). The reader takes some things that are meant metaphorically as literal when [s]he is not yet sure of the author's contract.

2) Damn, I'm-not-perfect Stage is next. That's when you realize--after calming down--that the advice is not intended as an insult, but was proffered for your edification. That can be a bone-jarring punch for some, others it can bolster their resolve to get it right.

3) Please-Everyone Stage follows. That's where you start trying to jam everyone's advice into your thirteen (and generally loose something of what you were trying to do in the process) instead of evaluating the advice.

4) Can't-Please-Everyone / weighing the cost Stage in which you start sifting through the critiques and realizing which advice is more valuable, and applying it. This is the stage where you take your time time applying what's said the first time, and don't rush to re-post. Here you know some readers will be lost (but you know some will no matter what decision you make) and you focus on the readers that are fans of your genre.