Older aircraft ie DH82, Auster etc, the compression comes up at a convenient point. They were designed to be started that way. They had a laid down procedure. It doesn't matter that much if you are behind or in front of the prop. More impotant is to be comfortable and not leaning into it.
Very importantly, communication between cockpit and prop swinger ie communication between all participants has to be 100%, and the procedure known and understood. That virtually (to my mind) precludes most multi engine aircraft at the minimum.