In this paper we investigate optimal points of time for task assignment in dynamic load balancing schemes. Normally final assignment of tasks to server queues is made at the latest possible time. The main reason for a late assignment is, that a dynamic load balancer can use most recent information about system and application state for the decision. In general however, assignment can be done at task arrival time, at the moment when a processor or server becomes idle, or when significant load changes in the system occur. We will elaborate preconditions and circumstances for situations, where it is advantageous to assign tasks earlier than necessary, i.e. to queue them at the servers. We verify the results in an experimental load balancing environment.