fourth year
If the system was designed with a recirculating loop, but there was never a pump installed or the pump is defective, then the sink might be the last fixture on the loop before it returned to the water heater. In that case, it would not get hot water until it had supplied all the other fixtures. After the kitchen water is hot, go to the other faucets and see if the water there is already hot. If so, then that may be your problem.
