When I last went, we made a list of sites we definitely wanted to hit but didn't plan the days. We rotated the responsibility of choosing the days dives daily. Typically, we went south and chose sites based on several things. For one, you might want to go to the sites furthest on the island, get there and see that it's too rough. This did happen to us, so we drove north until we felt comfortable with the surface conditions. On any given day we mixed random sites and sites which were on the wish list.
Going north to the park can end up being an all day affair.
When going north but not the park, we might do oil slick, karpata, and 1000 steps. We ended up skipping sites on occasion because of the parking situation or lack thereof.
Go have fun, wing it a little, and don't be afraid to adjust your plan even if you're at the dive site.