> Does visualizing time also fall under a number form phenomenon?

I think it depends on how it's visualized. Number forms are idiosyncratic two-dimensional visualizations of any numerical sequence. If the visualization is three-dimensional, it's spatial sequence synesthesia, which is a different phenomenon.

For me, months of the year are something like a sine wave, which is still a number form. The peak is in June, and the trough is in December.

Edit: According to Wikipedia, spatio-temporal synesthesia is also a thing. I think that's what you have.