I do not have a good answer to your question. April 20,1962 was the date of the Press Release for Jetfire. I don’t know if you could get one at a dealer on that date. They did make 100’s or 1,000’s before that date and I have always assumed they were at the dealers by April 20. That was standard protocol of the time.
Every article that I have read regarding the Corvair Spider states the were second to the market by about two weeks. You can Google many articles discussing the intro of the Spyder, all that I have read say a couple of weeks later than Jetfire. Date 1st at the dealer show room, I have no “facts”???