Completing Turn 2 of the Binding Coil of Bahamut should not lock me out of doing Turn 1 if I haven't done it yet this week. That's a horrible system.

A much better alternative is to have each Turn have its own lockout timer. The idea of only being able to access Turn 2 once you've done Turn 1 is fine (or being carried in by your party leader, also fine). But being locked out of Turn 1 because you did Turn 2? That's just stupid.