The subject of agitation is very deep - there are advocates of many dilutions of HC-110 and many agitation schemes. Just search HC-110 on this site. Generally one balances exposure with development dilution and agitation to get the desired contrast. As I say, you have a lot of reading to do.

That said, I think most folks tend to follow an agitation scheme similar to what Kodak recommends - every 30-seconds or every minute. I'd recommend picking one of those and developing a lot of film constantly that way until you know enough about the results you're getting to know what you want to change - if anything.
juan