If you are still having trouble, use the inverted song of time, put on the bunny hood, and look at which one the dog barks at, because that is the closest one.
Like VembersWind said look on your mini map. It'll show little white dots where all the aliens are. This will give you a good idea as to which one to focus on first.
Just make sure you are outside and not in the barn so you can see them coming. Make sure you are riding Epona, have a complete and fukk set of Arrows. Just keep going around in a circle close to the barn and you'll be all set to go.