Sexual compatibility is registered in the first moments you meet someone, since the sexual center is the fastest and most impactful of all.

You find a partner based on karma and your level of being. If you want superior circumstances, work on your mind so that you attract the person who will elevate you further.

As for a Gnostic wedding, for that you will need to find and be a part of a group for many years, one that maintains the three chamber system established by Samael Aun Weor.

The following lecture provides beautiful guidance regarding this topic. See the reference below.