Is it OK to masturbate to a picture of your own penis? Also, is it OK to edge?
The human brain is a complex organ that controls most of the body. It works primarily by association. Thus, when it comes to sexual arousal, things that you connect with sex triggers a reaction in your body that can be visually seen in erections and dripping of pre-cum from your penis. The problem is that there are no boundaries on the associations your brain makes to things that are declared to be sexual.
The problem is, do you want to fix such associations strongly in your mind? There are people who see shoes as sexual and don't feel like they are able to have sex with first looking at shoes. Do you want to get to the point that you don't feel like having sex with your wife unless you first look through old pictures of your penis?
There is also related issue. The brain tends to generalize associations to find new connections. If you train yourself to get aroused by looking at pictures of your own penis, there is a strong danger that you start using pictures of other men's penises to add "variety." This can lead you down the path of pornography.
Edging is the practice of stimulating yourself near the point of orgasm and then stopping. It is just a new term for an old technique that was taught to men who had problems with premature ejaculations. Edging teaches the body to hang on longer before ejaculating.
There can be a problem if you get too practiced at putting off orgasm. The body can only hold the aroused state for so long before it has to reset. It is possible to delay orgasm so long that you can't finish until after a rest period. That will leave you feeling very uncomfortable because the arousal has loaded semen ready for ejaculation and it has no place to go. You are better off letting yourself ejaculate before you get to that point.