Keeping in contact with hiring managers whose job offers you rejected

I just started my career as a commercial credit analyst in a BB. When I took this offer I turned down a few others which I would also have been interested in, but felt that the role I took would give me the best opportunity to move into the IBD eventually. I parted on good terms with all of them.

One of these offers was in a Fortune 500, working in their M&A team. I turned it down because a) the money was far lower, b) I felt that working at a BB would give me a greater opportunity to network and maybe take advantage of internal recruitment opportunities and c) the people in this team at the Fortune 500 all seemed to be former bankers - like it's something you do after you've done banking, not the other way around.

While I don't regret my decision, I feel that maybe I was too hasty in dismissing the offer. If I can't make the transfer from CB to IB, this might offer another backup pathway in. The hiring manager said something along the lines of "Maybe our paths will cross again" and seemed genuinely disappointed that I didn't take the offer, so I feel they wouldn't mind me keeping in contact or something.

Long story short, has anyone had any experience in retaining some sort of relationship with a hiring manager, preventing them from forgetting who you are but not committing to taking a job? I was thinking of sending an email every few months or so, but any advice would be really appreciated.