Looking at it this way at the most right now, the island is still being used on 5 out of 7 days. They could still get ships in on 2 more days. (Dream 2x, Magic 1-2x Fantasy 1x)
Assuming that
DCL builds more ships, and they stay in the Atlantic area, The scheduled would be shuffled to accommodate the ships.
For example
Fantasy Fri (eastern only Itin Sat PC)
Magic Sat (western only itin Sun PC)
Dream Sun (3 day itin Fri PC)
Wonder Mon (7day itin from Miami)
Dream Thur (4 day itin Mon PC)
NB1Tues (7 day that leaves on weds)
NB2 Weds( 7 day that leaves on Thurs