What are the right steps to turn this networking call into a summer internship

I was introduced by an Executive Director to one of his friends, who spent about six years in an M&A coverage group before transitioning to a Principal role at his family’s asset management firm in New York City. The firm has roughly 12 employees and manages approximately $500 million in assets.

We recently had our first call, and I intentionally kept it to about 10–15 minutes. During the conversation, we discussed his experience in investment banking, his transition to the asset management firm, and some general topics related to banking.

I’m currently a sophomore at NYU, and my goal is to build a genuine long-term relationship with him that could eventually lead to an internship interview or opportunity.

What should my networking strategy look like from here? Specifically:

-How often should I follow up?
-What should I talk about in future conversations?
-How can I continue providing value and staying on his radar without being overly persistent?
-At what point, if any, is it appropriate to express interest in internship opportunities at his firm?