Remove the pond plants from their bags and place them in some water (65-70 degrees) in the shade. This will allow the plants to replenish moisture that may have been lost during shipment. Your plants may be kept in the house in a container for a day or two before planting if necessary. Any floating plant or underwater plant can be put in your pond after the sun goes down the first day that you receive them. Make sure the pond plants stay damp and in the shade prior to being placed in the pond.
Many of our plants are shipped directly from a greenhouse environment. Just like any plant coming out of a greenhouse it needs time to adjust to its new environment outside with the direct sun and wind. This process is often referred to as "hardening off".