They should be right at the leech, like where the battens poke out, maybe 5 of them. You want them on the luff of the jib too, but they are key for setting the twist on the main. The top ones should be flowing about 90% of the time, but flipping behind the main every now and then. The combo of sheet tension/traveler setting it takes to achieve that keeps changing with windspeed and point of sail...if the top ones are flowing fulltime. you could maybe travel out and sheet in to drive the top of the sail harder, i.e. less twist. If you are already sort of overpowered, you might want to travel in and sheet out,getting them flowing, showing a power shedding, twisty shape.