To those that are new to Tesla production schedules, each factory builds cars in quarterly schedules and the first cars built each quarter are those that are to be delivered most distant geographically from the factory, whilst those that are to be delivered locally, i.e. close to Giga Shanghai in this case, are produced near the end of the quarter. Australian market cars are traditionally built quite early in the quarter as there needs to be time to ship the cars to Australia, move them to the different centres then prepare and deliver them. Tesla has done this for some time so they can make and deliver the maximum number of cars in any given quarterly reporting period. Tesla financial reports emphasis delivered cars so you need to make, ship and deliver to be recorded on the current quarter figures.
So it’s likely that most if not all of the Model 3s currently ordered have already been made as the Australian allocation doesn’t take very long to produce, perhaps just a day or so. Tesla also build a few cars to spec and there are inevitably some cancellations which is why there are sometimes inventory cars available but rarely at the beginning or middle of a quarter.
This is also one of the major reasons why Tesla don’t like to report monthly sales like other manufacturers as their monthly sales figures are lumpy due to this production schedule.
My guess is that if you want the fancy new chip in your new Tesla, you will need to delay your order to the batch to be built at the beginning of the second quarter.