I prefer to prime& paint first coat or stain and apply first top coat on anything I can before it's installed .Then after install fill any nail holes and apply the last coat of finish.Much easier and cleaner that way.
Nail holes? What nail hoes? I thought the newels and spindles are either being installed by drilling out the nosing to fit the dowel in them, or by putting screws in the bottoms and screwing them in the nosing?I prefer to prime& paint first coat or stain and apply first top coat on anything I can before it's installed .Then after install fill any nail holes and apply the last coat of finish.Much easier and cleaner that way.