Is the water that is in the pond muddy or clear and at your place how have temps. been? Will you be feeding pellets? If so the FH will eat them.

I would go ahead and add some pallets for FH to spawn in. I would do that as follows. Do not fix them in water that will be deep. Tie a rope or line to them and put them in the water. They will float. Anchor the line to the bank at full pool. That way as the pond fills you can pull the pallets back to near the current pond/water line ( keep them in water no more than 3 ft. deep once the FH go in). When the pond is full you can anchor them near the bank in 1-3 ft. of water where they will water log (or you can put a few big rocks on them to keep them in place). You may want to place some at different depths to match the water level as the pond rises and falls.