From what one of the Model X owners posted, it's important to remember that there may be options available early on, but it will push back your build/deliver date. Almost nothing will be "available" early on if you're not an employee/previous owner.
Using myself as an example, I placed my reservation in person at noon in Walnut Creek, CA. When I go to order, and start playing with the different options:
-If I put together a Model 3 75 RWD I'd get an estimated delivery of late November.
-If I tweak the same car to be a 75 AWD, it would bump my estimate to late January.
-If I decide the 55 (guess) has plenty of range but stick to a budget and keep RWD, it might estimate mid March.
-Or, if my finances are in order and I buy my wife a big boquet of roses, my P75D estimate is mid April!
This would all be based on receiving my invitation to configure around September (wild guess).
One of the reveal cars for test rides was AWD, I think (or certainly hope) that they are "done" as well, just manufacturing ease is dictating availability. You can order a $35k Model 3, you'll just be waiting longer for it.