Generally speaking, with enough experience and sufficient sexual frequency, a man can develop full control over his orgasm timing. He can keep going for as long as he and his partner would like to go. This presents an opportunity to, when he does decide to orgasm, do so with a purposefully driven level of precision, pleasure and overall intensity.
Mirroring the fact that opening type movements delay ejaculation, like opening the legs, expanding the body, relaxing your pelvis, and prolonged exhaling, the opposite can accelerate ejaculation. This means bring the legs together, clenching the PC muscle and tightening the hips and generally contracting your body position. At the same time, bringing the position closer to one with more skin-to-skin contact and proximity to her smell. Mentally, focus intensely on the sensation of her pussy on your dick. Recalling that the head of the dick is the most sensitive, prolong your thrusts to be deeper and to slide across the deep walls of her pussy, and less of a purely in and out action.
When you’re generally aware of where the line of no return is, you can play with it to intensify the ultimate release. Get near it and relax, switching to a less stimulating position. Repeat several times to bring yourself closer and more tightened in body shape and orientation towards her. It is good to leave some room for greater sensation, such as the possibility of greater proximity, a deeper thrust, some particular stimulation she does to you, some particularly arousing visual feature on her, so that when you decide to finally burst over the edge, you can at the same time add this additional stimulation to achieve a more potent orgasm.
Cumming is a joyous artform, treat it with its due respect.