I would definiately make the meat sauce a day ahead and fridge it, assemble on day (10 minutes max including making either a packet or from scratch cheese/bechamel sauce, or cheat and buy a jar) and cook on day and eat fresh.
You can make and cook in advance and freeze and reheat, but in my experience this can make it a little dry ...... always better to go fresh and reheating from frozen versus cooking fresh will be very little difference in time anyway. Hope it's delicious - sure it will be!