A method begins by a dispersed storage (DS) processing obtaining estimated future availability information for storage units and organizing a plurality of sets of encoded data slices into a plurality of group-sets of encoded data slices. For each of the plurality of group-sets of encoded data slices, the method continues with the DS processing module estimating an approximate storage completion time to produce a plurality of approximate storage completion times. The method continues with the DS processing module establishing a time-availability pattern for writing the plurality of group-sets of encoded data slices to the storage units based on the estimated future availability information and the plurality of approximate storage completion times. The method continues with the DS processing module sending the plurality of group-sets of encoded data slices to at least some of the storage units for storage therein in accordance with the time-availability pattern.