The cream cheese must be softened in order to make the mix. Otherwise it will be too firm to mix it and spread it into your serving dish. Additionally, you don't want it to firm back up in the fridge completely because then you won't be able to dip into it very easily. The best choice would be to serve it just cool but soft, or you can serve it warm if you prefer. Pour warm chicken on top of softened cream cheese and you'll have a delicious warm dip to serve.