Nitrile gloves last longer and are more durable than latex. Also what usually degrades the gloves is oxidation (exposure to air). If you can vacuum seal your gloves or put them in a ziploc and remove as much air as possible. As a caveat to the plastic wrap be sure the gloves can still quickly be removed in an emergency situation.
I was using latex. I usually just grab a fistful out of the box every month a two and stuff them into my kit, relegating the old ones to kitty litter duty. Nitrile gloves are tougher, at the expense of some sensitivity. I'll try vacuum sealing some latex ones, labeled with the date, test them over a hot Florida summer, and see how they do. Thanks for the tip.