When is the ideal time to release a song so it can become the song of the summer?

I’ve been humming this song at work and today a coworker asked me what it was— apparently he had thought it was a real song, but it was just something I made up. Hours later when I was in the break room with the same coworker, he hummed it back to me, and although he butchered it, I was flattered. He told me if I put some words to it, I could “have a serious ear worm on my hands.”

The song has a warm vibe to it, and I think it could seriously blow up if it gained traction in the summer months. I’m not very experienced in trends or producing music, so I’m wondering if the window on getting a song to be that big by June 21st has passed yet— if so I’d probably want to save it for next year. Thanks!