You can set that the Xbox does not completely switch off after the shutdown, but the remaining downloads finished loading.
That's clear.
In addition you go in the attitudes under system you select updates and downloads. There you put a tick at the items Always update my console as well as Always update my games & apps.
Under Power Mode & Start you set the power mode still on fast boot. This keeps the console in standby mode when it shuts down and automatically pulls the updates.