I think you're looking at this with some seriously rose tinted glasses. I find it hard to believe that Canon has very much stock built up for a camera that's still several months from release. Also generally the way stuff gets manufactured now with just in time component deliveries to the plant, they don't "build up" a stock of components before something gets made. It's a financial liability to set on a bunch of expensive parts months before you actually build a product. Parts are normally delivered to the factory very shortly before they're actually used to build a camera.
I also don't think Canon will release the camera until they have a good stock of them built up. They aren't going to release the camera with only a very limited supply to sell to people. As soon as the camera is released, people will be looking towards how many Canon has been able to sell to judge if the camera is a success or not. And not having enough stock on hand is a good way for Canon to look very bad from several angles, ie they can't build cameras quickly enough, also the impression that no one is buying their new camera, and finally unhappy customers waiting forever on their preorder. Releasing a camera before you have sufficient stock built up is a recipe for disaster.
Your first paragraph is an excellent synopsis of just in time manufacturing; with a little luck this virus may finally be the end for that dreadful method of operating a business (you're gambling your business that there will never be a supply chain disruption...or you can lay in some extra parts and be in a position to keep working during unforeseen events. Your choice...)
Your second paragraph also does an excellent job of describing how Canon is most likely to do things. And if they want to have sufficient inventory to ensure sales, they are not only making the cameras as we converse, the first batch needs to be in the shipping containers by the end of March to ensure they are in hand by July. Sailing time from Japan is around 20 days in good weather, longer in bad. It takes a week or two to consolidate the containers at the departure port. It takes a week at the receiving port to sort them and get them on their way, then another two weeks for the inventory to get where it needs to be. That's 2 months if everything goes well, 3 if it doesn't. (For low value products like toys, it is double this because the manufacturer isn't willing to spend extra for expedited service, which Canon most likely is).
Here's the weird thing - the initial units for sale will probably come in via air freight, which buys the factory a bit of time to fix any problems that crop up in the initial batches, or which appear in the QA testing of the first batches (that will have already been shipped to meet deadline). Unfortunately, it is cost prohibitive to air freight for really large quantities, so the ones made before the final 'first' batch is air freighted may have to be fixed here in the US.
As for Europe, the sailing time is longer and riskier (pirates etc).
Now maybe Canon can charge enough of a premium to cover air freight for the first 100K cameras or so; that would be an interesting thing to calculate. But even so, if sales/delivery are planned for mid-July, the cameras need to ship by late May/early June. Meaning production needs to start in April. 45 days from now.
I imagine the sales of antacids is high near Canon's factory at the moment.