Some updates will require your vehicle to be turned off for a period of time. In order to ensure you won’t need your vehicle, we recommend scheduling your updates for a weekly time that works for you. Don’t worry about forgetting — you'll be notified in the vehicle prior to your scheduled time if an update is ready to install. When an update is available that requires your vehicle to be parked with the ignition off, you’re able to schedule the day and time when updates are available. For example, many people might select 3 a.m. when they are sleeping and they know the vehicle won’t be in use.
From your SYNC® screen:
Press System Updates
a. Depending on your vehicle, this could be on the second or third page of Settings
Press Schedule Updates
a. If no schedule has been set, choose a date and time
b. Your set schedule will be recurring, so every time an update becomes available, it will be installed at this day and time unless changed. You’ll be notified in your vehicle when an update is scheduled, with an option to change the schedule.
c. If a schedule has already been set, you can come back at any time to change it