I (30F) have a crush (23M) on my worker

I (30F) work for a company that has many employees in different countries. Since we all do the same job in each country, one of my colleague (22M) needed my help. So we had a call on Teams. Because the issue he had takes long time to resolve, we had many calls every week.

He's quite a humorous person, and over time, our work conversations have expanded to include personal and everyday topics. A few days ago, he asked for my instagram and added me. And today for the first time, he made a sexual joke. Because of his age and personality, I see that he's a bit less mature than I am. However, every conversation we have excites me a lot, and since he won’t need my help soon, I know I won’t have this connection anymore. Even though he added me on Instagram, he hasn't sent me a message. I have no intention of telling him how much he affects me, but I don't want to lose the relationship we currently have. Since we’re in different countries, he's not someone I could have a long-distance relationship with either. But I cannot stop thinking about him, it is like this for weeks. Should I approach him from instagram now or later, or perhaps never?

TL;DR: i have a crush on my coworker but we live in different countries and have an age gap.