It could be that long anyway, especially if you want powerwall 3 (which is going to require an integrated system with the solar panels, and is not compatible with retrofit type installs, per Tesla).
One thing I have learned with Tech in general (which also applies to Tesla), is that never buy something DEPENDING on features that are "coming soon". Dovetailed with that, is trying to make purchasing decisions wanting "the new thing" whatever that is, and trying to time it.
I am not sure what your driver for wanting solar is, and I also am one who likes new Tech (and I work in IT), however, I dont think I want Gen 1 of Tesla *anything*. Especially not something whose lifespan is supposed to be measured in decades.
Dont get me wrong, I like Tech, and I think home batteries are cool, but I personally would not want powerwall 3s till they had been installing them for at least a few months, if at all (due to the seemingly proprietary tie in, with Tesla saying "we wont retrofit this onto existing systems").
I have 2 powerwall 2s, and I would buy these again.. If I was in the market now, and there was no actual driving date (like we had in CA for transition to Net energy metering 3), I would either move forward with powerwall 2s, or wait (months) if I intended to buy powerwall 3, to at least put "my ear to the ground" after some installs were done and peruse the internet so to speak.
TL ; DR. If the plan is to wait till powerwall 3, then you probably should wait to order instead of trying to time it such that you are going to be one of the first sets of product installed in your area for PW3.