I remember someone posting angles, measurements, and a picture/drawing for positioning my body on the bike. Is that in an easily accessible place (like a www?)? I’ll have my LBS do it, but I usually spend several weeks on the trainer tinkering with it afterwards.
There are formulas, yes, so when the fitter stands behind you when you are seated on the saddle, pedalling, and asks if you prefer the FIST or the BIG SLAM … do not fear …