There's a few things you can try that have worked for me in the past like edging, squeeze technique, and as a quick fix using a numbing spray like Promescent or Stud 100. Getting comfortable during intimacy is important and I noticed that I would always be too anxious leading to a faster than desired climax for me and my partner. After a few "good" sessions you really start to relax and become more confident. Combining edging and using a numbing spray really helped me get there.