Yep, what everyone else has said: use Pasante, Mates/Skyns or Skins, and have a few larger ones in stock (it's surprising how 'small' some men are who need an XL condom - sometimes it's more about shape than length or girth).
Only you will know if you need to use lube, but obviously do so if necessary, and don't be afraid to top up if he lasts a long time.
Sometimes if the sex has gone on for 15-20m, I use a change in position as an opportunity to change the condom, as sometimes they can dry out.