I am currently applying for membership for the Mayflower Society. Your question sounds like you had not applied yet, so I would suggest you at least start the process. In my state chapter (California) it has worked like this so far. I filled out a worksheet sent it in, and waited about a month and a half for a response. Then I got the preliminary membership application, sent it in and waited about a month. Then I got final application last week, and am filling it out now. I need only six vitals to document my line, and I they gave me a year to get them, but will extend the application time if I show I am working on it. So in your case, if you have to wait five months for a vital, you would still have time to complete the process for membership and receive the document you need. It seems to me, the Society is aware of some of the long wait times for documents and accommodates that time for the membership process. If you know your line is solid, apply now and gather your documents while you are waiting. Good luck!