His original question sounds like either of two......... dial in aileron trim before rolling, or hold aileron before rolling. The wording, "setting up" suggests it's done at leisure beforehand. Of course, the detailed account of which aileron up AND which down confuses even more. After all, experienced modelers wouldn't feel the need to explain aileron trim that is done with a click of the trim button.

Neither is needed and both will cause problems in more situations than less. And trimming ailerons beforehand certainly isn't needed either. So before or during, neither is needed.

Beginners really shouldn't look for crutches for a maneuver that is so easily controlled with the proper technique.

Learn to ease in the throttle and steer with the rudder. It saves you so many airplanes.