Medium Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Company Policy; Human Factors
Pushing back we were told to push to 'the 16 spot' by ground.  I told the ground crew 'brakes released; cleared to push 16 spot' and they acknowledged and began the push.  We were cleared to start one and did so.  They pushed us back only just off the gate and asked me to set the brake.  I depressed the toe brakes and said 'brakes set'; but before I set the parking brake I asked right away if they were going to push (much) farther to 16 spot.  They said this is where they always push us.  I never said 'cleared to disconnect' and they had removed the tow bar right when I initially said 'brakes set'.  I realized we were starting to roll and they asked again if we could set brakes because we were starting to roll.  I did; and then asked ground if we could just disconnect there because the crew was already disconnected and they said that would be fine.  There were no further issues and we were waved off and on our way.It would help if the ground crew received the 'clear to disconnect' first before disconnecting.  It would also help if they didn't know where spot 16 was; that they ask instead of just pushing where they always push.   I wasn't sure why they asked me to set brakes initially since we were nowhere near '16 spot' which is why I just got on the toe brakes assuming we would continue; and that we were still connected to the tug.  I probably should have just set the parking brake so we would all be on the same page and then figure out the confusion.
During pushback; a tug crew failed to push the aircraft to the proper location and disconnected the tow bar before obtaining clearance from the flight crew. The aircraft momentarily began to roll before the flight crew applied brakes.