Be careful. If the prevailing “deal” is for $X then resale will almost certainly adjust to be LESS THAN $X.I can make a suggestion. There are some really good deals out there on some new cars with factory rebates and discounts. You could pick one up to use in the interim and just sell it when you get the Rivian.
An example, I found a new 2020 Malibu a couple of weeks ago that was 6K off sticker. If you run that through KBB the trade in value is worth more than we paid for it with 10K on the odometer. If you find a deal like that, you would probably be able to have a car for 6 months put 5 or 10K on it and sell it for almost what you paid for it.