I would assume the longer schedules and turn around times are possibly to allow some slack in the schedules and to absorb any delays that may creep up as sometimes happens when a new aircraft is introduced into a fleet.
You might find that as the airline gains more experience with the type and more crew are trained that tighter schedules and weekend flights will be introduced.
Perhaps the initial weekend periods are to allow for crew base training or similar?
My 2c (at R11 to the $) worth!