There are a few ways to accomplish this. More info on exactly what, why, and when you need to happen would shed light on which way would be most appropriate. Start the swell right away, wait until you play something, etc.?
My first impulse would be a dedicated Vol/Pan block that is active in the target scene, and bypassed (set to 'Thru') in all other scenes. A 'Scene Controller' (or 'Control Switch') attached to the 'Volume' parameter with the Damping 'Attack' parameter set to 1000 ms. Set the 'Scene Controller' (or 'Control Switch') to be !00% (or 'On') in the target scene, and '0%' (or 'Off') for all other scenes.