it's December 1, which means 4 weeks is December 29, and we're talking Tesla time. I am highly doubting anyone ordering now would get their car this month. I'd love to be wrong, but that's realistic in my opinion.
I estimate 300 based on ~30 people on the forums saying they got their invitation, and guessing based one someone else's number that 10% of people would get on the forum to post that ( I actually think a higher percentage would, but I'll use the low end). Maybe there are a few more employees waiting, but they've had their invitations open for months, so I'd guess many would have already placed their order and had it fulfilled. I would think MOST employees would either wait for AWD/Performance (if they're high paid) or wait for standard battery (for the regular Joe working in store/factory). Maybe double that 300 to 600, but I'm doubtful at this point, and I was the one saying over and over that I was sure I'd get mine before end of year for months now. I only accepted that I wasn't last week. (non owner, 20th in line east coast).
I think the ramp up MIGHT start this month, but I don't think anyone ordering beyond this week should expect their car before January 1. I'd love to be proven wrong.