Air carrier First Officer reported receiving a GPWS terrain warning on approach to BGR.

Narrative

Aircraft X was going to BGR airport. Cleared for the Visual runway 33. During the brief; the Captain briefed the terrain just right of the course between elsuh and cuvot at 1251 feet. He briefed that we would set 2300 alt for cuvot and still be clear of the obstacle. Plane alts cap at 2300. As we were coming in the gpws went off. Captain immediately disconnected autopilot and gained altitude. Once gpws was off and it was verified we were clear of obstacles we reset up the approach and were stable before the faf.Although we were in the process of alts cap at 2300; I believe that the gpws was reflecting the descent rate previously shown and assumed we were going to keep going down and would hit the obstacle. Use a slower descent rate and wait till fully established on the final approach course before starting a descent. Also wait for the calculated top of descent. In the future we could have set 3000 feet and waited till the localizer was captured and followed the snowflake instead of descending down to the faf alt to avoid gpws warnings.