How often to email an employer about an interview?

There's an analyst position at a MM firm that I am really interested in, which I found out about through a reference and cold email several months ago.

After emailing and speaking with an associate, I met with him for an informal meeting. It went so-so, but he was pretty cool. He said he would get back to me in the next few weeks or months about a possible interview.

I emailed about 6 weeks later, just to reiterate my interest and ask if there was any updates regarding setting up an interview or their process. He told me they were still having informal meetings with potential candidates, and will let me know when they move on in the process, but aren't planning for interviews until maybe the spring.

That was about 6 weeks ago, and while I haven't heard back yet (nor did I really expect to), I was wondering if I should send an email just to ask about their plans and if they are close to setting up interviews. I don't want to come off pushy or annoying, but a friend of mine said it's good to check in and show your interest and might actually look bad if I don't check in from time to time.

What do you guys think? Should I just wait it out, and if they want to interview me they will let me know when the time comes? Or should I go ahead and send a friendly email to ask about their status or plans? I'm pretty inexperienced when it comes to these situations and of course don't want to mess up my chances, so thought I would ask for advice from WSO. Thanks in advance!