Holding back can be a turn-off for some, so I’d say this is something that’s worth discussing with your OH, if you haven’t already to see if climaxing quickly is taken as a compliment, or seen as an issue to work on.
If I’m planning for a longer session, I find masturbating (it can be fun to get someone else to help!) around an hour, or half hour before (this varies for different people), is a good way to releive tension and delay my climax.
With the refractory period (recovery time) and sleepiness, out of the way, I feel more relaxed, and find the excitement, urgency and sensitivity builds less slowly, though still with a really satisfying finish.