Guesswork was how I figured mine out, and a bit of process of elimination. I tried Molace first and no result, so then I figured most likely it would be on an Armacup ship, so I just matched up my build date and departure dates from Shanghai and waited and got lucky
Now that I've received the "Your Model 3 has arrived in Australia" message I've relaxed a bit; it'll take a bit to get on a car carrier and get down here to Canberra from Port Kembla, so I know it'll be roughly within the EDD I've been quoted. I just need to coordinate all the other "moving parts" e.g. work trips, stuff I need the current car for, and how to slot in selling it and settling my Tesla invoice.
FWIW I checked the RAV early and it wasn't in it, but checked again just by coincidence a day before I got the "it's arrived" text message, and found it had been entered about a week before that. I'd already had the VIN and the build date for about 2 weeks prior.