This guide is written for Samsung tablets. If you use another Android tablet brand, some setting names may differ,
Notifications
Go to Settings > Notifications > Do not disturb, and turn on Do not disturb.
Go to Settings > Notifications > Advanced settings > Show notification icons, and choose None.
Display
Go to Settings > Display > Screen timeout, and choose 2 minutes.
Note: For large tablets (Samsung S7), also go to Display > Adaptive brightness and turn this off.
Date & time
Go to Settings > General management > Date and time, and check the date and time are set correctly.
Software update
Go to Settings > Software update, and choose Download and install. Your tablet may restart if an update is installed.