Actually there were statements about PRUSA delivering 3000 units per month and at the Maker Fare they had that poster stating 6000 units per month (which sounds a little like marketing hype or at least a peak figure)
200 printers printing, and 24h for printing the parts for a new printer yields a theoretical capacity of 6000 printers per month - but that assumes 24/7 production, no weekends, no maintenenance. But 100% utilization does not seem realistic, 50% would be the stated 3000 printers, and that sounds very reasonable, with potential to crank up the production.
The big unknown number is the pre-orders for the MK3, and the delivery of 3rd party components.
I think it is safe to assume that the number of pre-orders is at least as high as the normal production volume, then it's a simple calculation.
It's 6 weeks since the MK3 was announced, if they can produce as fast as the orders came in, then just add 6 weeks to end of November if you order now. That's beginning of January, but with christmas and the supposedly high interest in the MK3 I am actually surprised that they are stating a delivery in January for orders coming in now.
Bottomline - it looks like Prusa is confident that the deliveries will really start in late November and that they can produce in large volumes from the go.
We'll know more in 2 weeks.