Yes, there is a lot of method, technics (and theories) how to find a thermal lift. What John described is one of them. What I’m doing while on tow behind the plane, just after take off and first (usually) right turn I start paying attention for when “a normal” raising number on vario for tow suddenly jump up. Which mean we are flying thru lift. That’s the moment where I look down on earth, remember the location. Especially when I’m close to release altitude. It happened to me many times that reaching (for example) 2K I release with no lift around me. So immediately flying back to last know position of lift we pass thru. How to find the lift when you fly free, that’s for another (long) article.