"West coast" deliveries are all those that Tesla can ship by truck directly from the factory in Fremont, California. "East coast" deliveries are all those that Tesla ships by rail to Chicago, Illinois and Birmingham, Alabama, and then by truck to their delivery sites. If you are a closer truck drive to Fremont than Chicago or Birmingham, then you are "west coast". Otherwise, you're "east coast". It really boils down to whether rail shipment is involved because that has such a significant impact on the way the logistics work.
As St. Louis is a 5 hour drive from Chicago and a 31 hour drive from Fremont, you're considered an "east coast" delivery. That suggests a November timeframe. Note that "west coast" deliveries apparently happen throughout the quarter, but when Tesla goes into crunch mode to pack as many deliveries as possible into a quarter, they focus on deliveries local to Fremont because they can do those so quickly.
A twist in this is the rising interest rates. These are expensive vehicles. Some people are simply not going to be able to afford a Tesla because of the increase in monthly payments. That should shorten the wait time for those who remain, though I have no idea how much that might be because I don't know the finances of the average Tesla buyer.
