I purchased my gen 3 wall charger from the Tesla shop on a Monday, it arrived by the Thursday to inner city Melbourne.
I delayed the electrician appointment a couple of months, but when they came the install was done within a morning. My run of electrical cable (from switch box to wall charger, through the ceilings and walls) was less than 3m total. The further you need to run the wiring, the longer (and more expensive) it’s going to be.
I’m guessing with the current tradie market; the lead time for an electrician - from booking to installation - is going to vary a fair bit.
The biggest risk i think you face in getting it installed “early” is that Tesla release a gen 4 wall charger after you’ve had it installed. But there’s been no talk or rumours of any new wall charger hardware being in the works.
And of course you could go with an alternative non-Tesla wall charger