Buy a color wheel from your paint manufacturer. Once you have walls, paint a large sample of your grey on wall. Then
Icky your white. I like a pure white for ceiling, like Ben Moore Decorating White. But you should really should get that wheel to decided trim.

Definitely white, as the cream could "yellow up" compared to the gray, even though it is a warm gray. An alternative would be gray on the trim. See Houzz Photos under "gray walls," and you will see some gray, but mostly bright white.