Question: how would i know that i have premature ejaculating problem before having sex

One way of testing is by masturbation.  How long do you last doing that?  Does it end quicker than it should? 

There are ways that you can improve the longevity of your erections.  First off, you could try working your way to orgasm by masturbation, then when you are about to orgasm, stop for 30 seconds.  Continue masturbation until you feel you are going to orgasm again and stop for 30 seconds. Repeat until you are ready to ejaculate.  By doing this, you will increase the threshold of pleasure and train your penis to hold on longer.

There are also supplements that you can purchase online that help with premature ejaculation.  One that is clinically proven to work is the Roaring Tiger Virility Supplement.  (www.roaringtiger.com)  It's herbal content helps men acheive longer, more pleasureable orgasms.