"I bought a few spruces to replace old dying plants. Should I wait until spring to plant them?"
This is actually a good time to plant trees and shrubs if you live in an area that still has six weeks before hard frost. If you do, plant them now, but make sure the soil has been well-prepared and remember to water them two to three times a week. Do so right up until the frost warnings start, since they will be transpiring, or losing water, all winter.