As others have said it totally depends on the airline concerned. Some I have come across use brakes off, another uses anti-collision light on. Another has the ACARS set to record departure when the front wheels move 3 rotations forward (this stops the dispatcher trying to avoid a delay by asking the captain to release the brakes before the door is even closed). It is down to how the operator wants to fudge the figures to make their on time departure figures look good.