Wow - I know how tough it is to leave your kid in a new place, even when you're completely confident of the care. This must be really hard for you.
You're talking about two sets of issues, though - how well the school meets your needs as a parent and how well the school meets your child's developmental needs.
The issues with the start date and dismissal times are unfortunate - but unless you're in a position to yank your kid out and find a more accommodating program quickly, you may have to get through those. (But I wonder what the regular dismissal time is? Is he going home an hour early? Three?) And if the program overall is a good match - convenient, affordable and shared values - then I'd probably suffer through the initial adjustment. It may be that the school has a wait list - many in our city do - and they can be rather inflexible because, well, they *can* be rather inflexible.
I'd be more concerned about your gut instinct that the teacher isn't doing much to ease the transition. Again, it's tough to separate your tension from your child's reaction. Most small children are shy and distant in the situation you described - if he's picking up on your discomfort, that's even more true.
If you know other parents, I'd get in touch with them and ask their experiences with Ms. Tough Cookie. But if you don't, I'd schedule some time to talk privately with the school's director. If your reasons for choosing the program were sound, then it is worth investing a little bit of time before starting the school search all over again.
Honestly? I'd be pulling my hair out if I were in your shoes. But I'm not sure I'd walk away just yet. There's so much emotion attached to first days of school for *everyone* and sometimes it takes a few deep breaths and a confidence that most kids really do enjoy pre-K ... after they get over their initial adjustment, and we figure out how to re-juggle our lives to get them there and back every day.
Good luck.