If you can't get more intel the night before, just go to where you saw them last and get some decoys out 30-40 minutes before they can see you, do it quietly. Get set to shoot and wait for them to wake up. I have killed birds many times without even calling, because they see my three hens and jake, and just fly down and run in for a fight. But a little light calling doesn't hurt just to make sure they see your decoys. I've had up to three gobblers launch in my direction before and race each other too. I love to watch them fight, and it gives me time to sort out which bird I want to kill.
Jake is a coward it seems, and always just stands there, so I always have to finish it myself.
You have to be very well hidden though and don't blow your cover, because they will be looking your way, gobbling from the roost and studying those decoys for maybe a half hour before they decide to fly down. And they may come from any corner of the field.