Dear Teamviewer developers!
When do you plan to release teamviewer 13?
I don't think anyone can actually tell you that. But I can tell you (from my experiance and a touch of research) that v12 was released for public beta and License upgrades in October/November of 2016 and actually released in December. As was v11. From What I can see Usually they release their major revisions in December.
https://en.wikipedia.org/wiki/TeamViewer#Version_history
https://community.teamviewer.com/t5/TeamViewer-12/Team-Viewer-13-Beta/td-p/16430