Putting a numbing product on the head of your penis before putting the condom on would be a good thing to try, all right, but as was said above, not the products you mentioned! If you put Icy Hot or Bengay on your penis head and proceeded to have sex, after about 5 thrusts you would be yanking off the condom and fleeing to the bathroom to flood your "head" with cold water! The sensitivity--of one type anyway--would be greatly increased rather than decreased. In fact, the intense heat stimulation from the friction might still trigger an ejaculation. But if it did, I don't think there would be much of an orgasm involved -- probably just a playing out of the ejaculation process by "auto pilot" reflex as you were on your way to the bathroom!
I believe that the effectiveness of the "retardant" cremes that are available at the pharmacy will vary with the individual. It's possible that an early ejaculation could still be brought on purely by the physical friction to the head, without regard to the "pleasure" sensations involved. But by all means it's worth a try--certainly no harm would be done even if it didn't work as well as hoped.
Well, actually you should try applying such a creme privately and masturbating with it, or at least just applying it with an erection, before using it in intercourse, to make sure you don't happen to have an unlikely allergic reaction to it. That's true with any "application" medication that's to be used on a sensitive, nerve-ridden area like the penis head.