Wednesday and Friday, Oct 14th and 16th, look like the best weather days- my plan is to set up my table of drawings in Union Square unless the weather changes. It usually does, but I'll post if plans change.
I don't know if 6am will be early enough to see the people starting to throw down milk crates to save their spots, but that's when I'm getting there. I have no idea when the squatting begins, but the two times I've set up a table of drawings at the park, there are crates and tables blocking off spots where vendors never came. I thought that was obnoxious.