Really the first thing is to not get too stressed out about it as the more it plays on his mind the more nervous he'll be and ejaculate sooner. The best thing to do is experiment, so when having sex when he gets close stop for a minute and if possible try the squeeze technique (when he feels close to ejaculating squeeze the end of his penis, at the point where the head joins the shaft, and maintain the squeeze for several seconds, until the urge to ejaculate passes.
But alot of this is psychological the more you worry the harder it is too last, that'why these major sprays and pills used for lasting longing contain anti-depressant chemicals.
Lots of support and pratice.
I hope this helps