On my invoice that the dealer gave me and on the website it is showing order number 0001. Does that mean I have the first order? I ordered 03/27 (I’m aware people ordered prior to 03/27). do other people have the same on their sheet?
order number has nothing to do with how soon you ordered, it's basically random and has no bearing on how soon/late your order is built or anything else
I had an order like 65983. So I think it's random, or local/tied to that dealer.
It is a good idea to save every scrap of paper. Not much physical documentation is created these days, but whatever you do have, it makes for good keepsakes, provenance, etc.
If you can't physically keep something, try to get a photograph of it.