Dallas changed its practice time for Thursday from the usual 2:30 start time, to 6:30. They're still scheduled to practice for three hours.
Today (August 4) is the first day that free agents who signed with a team can practice, but the new league year isn't scheduled to officially begin until 3:00 CT. Had the Cowboys begun their afternoon workout at the normal time, their free agent signings (guys like Doug Free, Gerald Sensabaugh, Abram Elam and others) would not be able to participate. The late start time allows for some leeway in case all the i's aren't dotted and t's aren't crossed by 3:00 sharp. That is also the deadline for the Cowboys to be at or under the salary cap, and they're expected to do so, potentially with the restructuring of some of the team's bigger contracts (Tony Romo, Miles Austin, DeMarcus Ware).
During training camp, every day feels like every other day. This day will be different, and you can see how different if you watch our coverage live from San Antonio at 6 and 10.