A workflow management system (WfMS) supports the coordinated execution of simple activities (tasks), assigning them to human or automatic executors (agents), to achieve the goal defined for a business process. The workflow scheduler performs task assignment policies: temporal aspects, such as availability time and skills of agents, deadlines for task completion, constraints over timestamps for task activation, periodic constraints cannot be neglected. By this paper we propose a temporal workflow scheduler which pervasively considers all the temporalities affecting task assignment policies.