Hi Alvin,
Set a time. For example lets say 20 mins initially. So you will start with first session and lets say you feel like ejaculating after first 5 mins. Then you stop. Again you stimulate yourself, for say 2 mins then you stop. Like that do for 20 mins.
Slowly with time and other practices you will see that the initial 5 mins will build up to 10, 15, 20...
Then automatically the overall time also will improve to say 30 min, 40 min, 1 hour...
In the beginning once you have a tantra session you might feel like having one more again in the day and end up losing it. But with time, you wont be feeling the need of one more session.
You can see that change for yourself, when the staying ability is improved, you will clearly feel it. But as Victor said, not losing your energy is more imp than doing heroic things like stimulating lot and controlling it. Thats why AYP says, the time to recharge (between one stimulation and the next) should be enough.
For me adding siddhasana has helped a lot in this improvement. I can confidently say holdback method works, because I have seen practical results for myself.
Thanks, Near
Genes are a result of karma RATHER THAN A CAUSE OF IT - Yogani