An A319 First Officer reported taxiing before clear of men and equipment after pushback; resulting in contact.

Narrative

Inbound flight was late due to lack of available gate. During pushback from gate the ground crew informed Captain that some hand signals would be used although the ground crew had been communicating with the Captain via interphone. First; then second engines were started. About the time the second engine stabilized the ground crew attempted to communicate with the Captain again via intercom to call operations. We did. They asked us to try and find a wallet that an inbound passenger forgot on board. We contacted the cabin. They could not find the wallet. We advised operations. This took several minutes. After this was complete the Captain asked for taxi clearance. We received taxi instructions. As the nose gear began to turn we heard a loud bang. The Captain instructed me to shut down both engines. The Captain asked the ground crew if anyone had been hurt. They said no. The Captain asked me to request assistance and emergency personnel from operations. I did not see a tug or ground personnel when the Captain asked for taxi clearance. The concern for on time; inability to communicate with ground crew; and not following SOP lead to this incident.