I think it very much depends on how dog savvy your cat is, and whether the puppy has been raised around cats. My cats had got to know dogs who were very gentle with them, and my own dogs were so tiny as pups that my biggest fear was that the cats would see them as prey. I made sure the cats' routine was maintained as closely as possible and that they still got plenty of attention, as well as ensuring safe accessible places out of puppy reach and escape routes where necessary. Until the puppies could manage stairs the cats could always find peace upstairs, but they quickly established that play was by their rules - one quick hard smack without claws was usually enough.
If your cat is less accustomed to close contact with dogs I would take things very slowly. A safe space is a good idea, but take care he doesn't become too isolated. I would introduce them with the puppy crated, and let the cat set the pace. It may take several weeks, or even longer, for him to adjust, and any chasing or pouncing will make it much more difficult - the more you can control things in the first few days the more likely you are to eventually succeed. A Felliway diffuser can help with some cats, but the most important thing is to keep the cat's life as unchanged and stress free as possible. Start making any necessary changes now, as Gwendalion suggests, so that your cat has time to get used to them while things are still peaceful.