I got my second vaccine shot Valentine's weekend and had a positive antibody test (the long term antibodies) this past weekend - basically 5 months. And it was pretty evident way before the 10 minute timer was done. Of course, they say everyone is different, and that not having a positive result doesn't mean that you don't actually have antibodies, so..... But that at least gives you a real world example.

Personally, I would do it as soon as possible - 4 months before your return home. Naturally, if you do that, the rules to the game will change before you go!

Keep Smiling!!!