Both Nikon and Canon have warned that there won’t be too many new cameras popping out of factories even after the official shipping dates, but Canon can brag that your wait can start 18 days earlier, as they plan on notionally shipping some units on the 27th of November. Nikon announced this morning that it will start mid-December.
This race of turtles will likely extend for months. The Canon R5 too roughly a year to finally become commonly in stock across all regions. Even as the R3 is certain to sell fewer units, it may take that long to become freely available. Just now, the Sony A1 – launched in January 2021 – is becoming sporadically in stock beyond existing wait lists.