Air carrier First Officer reported uncommanded aircraft movement due to non-compliance with ground crew communications and SOP's during push back. Brakes were set to regain aircraft control.

Narrative

Departure gate was listed as XX. Crew learned upon arrival at airport; aircraft was parked at a hardstand and were delivered to stand X. Note: XX had no correlation to a JeppFD Pro AMM parking location. Stand X is noted in 10-7 pages corresponding to gates XY or XZ. Preflight and passenger loading were normal. A 15 minute delay occurred (assumed) for passenger boarding and attempt to resolve missing cabin amenities. Preflight and Before Push checklists were completed. ATC clearance; communications with ATC (Delivery & Ground) were IAW 10-1 and 10-7 pages and engine start clearance received. Ground crew communications called for brake release. After completion of engine start; aircraft began to move forward slowly without any communication from ground crew. The movement was verbalized and query was made on flight interphone ground crew in which there was no response. Brakes were applied to stop forward movement. All crew members thought we were under push/pull ground crew control and connected to tug. Ground crew did not advise of headset disconnect nor did normal push/pull communications occur. Expected communications did not occur. Language and absence of specific coordination procedures of push/pull & engine start/taxi from hard stand at ZZZZ were factors.