I guess it would depend on what that team member was responsible for. If you could get the work done without the team member I would work toward making forward progress. You could use the RACI matrix to clarify whether that person needs to be “consulted” prior to a given decision or action step. If their presence is vital to completing team deliverables you might be in a position to postpone meetings. But if the team can make progress in the meantime they should be sticking to the agreed upon time line.