I don't know why people want an early boarding time. Rooms aren't ready. What can you do?
I sailed on the Enchantment in August from Baltimore. We got to the port maybe 12:00 p.m. By the time we got on, we had to wait a little bit for our room to be ready. We dropped off carry ons and went to WJ.
For April cruise, our flight gets in at 12:30 p.m. and then we'll head to port. Hopefully by the time we get onboard, our room will be ready.
I think you've got a good plan. No reason to get onboard the ship early. Sleep in and relax.