As has been pointed out, cock ring size is critical for wearing after the penis has returned to its flaccid state, as well as before. Idealistically, the ring keeps the penis bigger than when flaccid, so it's difficult finding just the right 'fit'. My advice is to keep searching for the proper fit, which might mean buying several rings.
After a session of jelq
uing my ring will stay on a day and night or two before a testicle drops out and I remove it --- eeekk, the ring! Daily PE keeps my cock big enough to avoid that and the ring stays in place until I skip a couple of days. I hope this gives you some help, zeus. BTW, a sexy name, man!