It's a nice trick, but it when you look at it, it falls flat.

Wedding invitations list the bride and then groom. So the bride's name has to end in "son". If see a wedding invite like this, you'll see what I'm talking about. It's the same for announcements like "Ashley and Chris have chosen their day", or even engagement announcements "her engagement to him".

If JJJ Sr. he would also have the Sr. attached to his name in the wedding invitation. Especially since JJJ Jr is a much more famous person in this context (being mayor of the city at least). Even moreso because he is attending the wedding.

Also, the date says 2009, which we assume is the present day for Spider-Man.

A popular theory I've seen have been that it's an invitation to Peter and MJ's original wedding. Doesn't work because of the time. Another is that Peter and MJ will marry. Doesn't work because Marvel isn't going to marry them. It destroys the whole purpose of BND.

The invitation is going to be for May and JJJ Sr. Marvel is just teasing the Peter/MJ thing in hopes of getting people to pick up the issue.