The best way to find this out for yourself (because it does vary) is to not be worried about going over. You can ruin it if you want, that’ll keep you hornier. But the main point is that you’ll only really learn what a ‘hard edge’ is for you if you’re seriously at risk of having an orgasm. So decide it’s okay to cum if you do by accident and just spend a while seeing just how far you can take it without tipping over.
Check out the tip on breathing in the last post too, that’ll really help.
But really, a big part of this is learning more about how your body and sexual response work, which is brilliant because millions never do, and so miss out. So don’t worry if you accidentally cum, that just means you’re genuinely pushing yourself as far as you can. And then learn to just dial it back that bit further so you don’t go over that edge.
From a technical point of view ANY masturbation without cumming is edging. Even if you just fiddle for a couple of minutes and never get near to orgasm. While you don’t get that rush of a hard edge, it’s all still stimulating you and getting you horny and wet, and keeping you topped up so that you feel good and experience that ‘denial high’ we all talk about.