I think what is actually required might depend on where you are, as in, what insurance laws are in effect where you are. In California, where I am, we can upload CURRENT insurance, because you have 10 days to report a new car purchase to your current insurance. This means that, when you buy a new car, the vin does not have to be listed on your insurance to actually be covered when you drive off in the car.
I do not believe its the same in every state in the US, as I believe I have read here that some people have had to get their vin assigned and put it on their insurance prior to picking it up.
In any case, this should not hold up your order, as you dont have your VIN yet, and your insurance company will want that to add the car to your insurance. I dont think it holds up your order at all, but might hold up your actual pickup of the car, so make sure you know the process for adding a car to your insurance from your insurance company (and more importantly getting proof from them its covered). Is it contact your agent, and they email you proof, is it fill out something on some website and they send you proof (etc)?
Just be ready to add it on the morning of your pickup appointment and get proof that its added and you should be fine.