We're happy to leave the exact details up to you! The ferry's control panel is complex and won't quite function in the way Bucky expects it to, though. And, hm, it seems as though Crowley's attempts to mess with the controls haven't exactly helped with that.

In any case, we imagine the ferry-ramming will happen rather suddenly (as we figure Bucky would've tried to stop it if he had the time). Whether it jolts off after a moment of messing with the controls or it's an immediate response once Bucky starts piloting is up to you!