Not a trainer, but...
Years ago, I messed a lot with convergences. Staggered patterns or single point. Close convergence, far convergence. The I started to set convergence according to my usual "mission profile" for each plane, i.e. buff hunters long convergence, furballers close convergence. But as I fly many different planes in many different roles, that created more problems then it solved.
So after a long time of testing this and trying that, I finally came to this:
ALL guns in ALL planes: Convergence 350. ( I prefer to get close to kill, but I also shoot at medium to long ranges, if necessary. I found D350 to be a good allround solution)
Exceptions:
Hurricane I, Spitfire I, 109E: 250
Me 262: One pair 650, other pair 250 (I always shoot all guns for maximum "shotgun" effect)
When I look at my hit% and kill/assit ratio... well, I can't complain

YMMV - convergence is a quite "personal" setting, and depends on a lot of factors. Just don't make it too complicated. Follow the advice given to you by the others in this thread, and then stick to it. Get used to it. No kind of convergence setting is doing any magic.