Hi Dave. I'd wait until seeds are germinating outdoors. Once you see new weeds emerging in the borders, then I'd put it down. If your dips are turfed, you'll need to remove the turf first or the repair will just blow away. remove the existing turf and rough up the surface, then apply your repair medium and then put a bit of chicken wire or plastic netting of some sort down over the top to protect it until it gets established. That's what I would do. Good luck! :)