IMHO, you should wait until there is an appropriate opportunity to do so.
I waited a year and a half to tell my twin flame who she was to me (even though I knew she was my twin just before first introducing myself to her).
I was trying to figure out how to tell her without scaring her away…
One evening she simply asked me if I knew who my twin flame was. That was my golden opportunity! 🙂
You want to be certain that your person is ready for it. You also want to be very certain that they are definitely your twin flame and not you trying to put a label on someone who really isn’t.
Please do your research thoroughly…check in with spirit a hundred times to verify this and trust that your golden opportunity will come to pass!