Focus on pushing energy up your spine and into your brain to prime the brain-tip-antagonism
Repeat MEGA and QUICK flexes. If your PC muscle seems difficult to flex, then simply focus on flexing the entire floor area.
Practice moving the ejaculation energy down from the tip into the root and up your spine into your brain. Always practice to at least move it behind the PC muscle to lock it up.
Practice PULL flexing to give the pressure of the orgasm a way to escape up your spine and do not let it sit in your root. You must allow the energy to drain or it will either push ejaculate into your bladder or out of the penis.