Personally, I prefer to define a century as 100 miles, completed within a 24-hour period of time, and done as "all-at-once" as possible.

Breaks are allowed, of course ..... but you do have to count them in your total time!! So if it were me, I might count that as a century, but my total time might be 12 or 15 hours or however long it took you to do all that.