Windows Updates
Microsoft pushes out updates every month that requires an update.
Follow the steps below to make sure you can schedule it to when works for you as well as not having it forced upon you.

Your computer will warn you when you have an update upcoming. In the above image, a little update symbol appears in the bottom right corner of the screen with a little orange circle. Other ways might be a bigger notification telling you that your computer needs an update.

Once you click on the notification, it'll take you to the Windows Update settings page. Here we can see the important information about the update.

It tells you a few majorly important things. The estimated time it'll take to complete. When the device needs to be restarted by. And the options to restart.

Clicking the arrow reveals the option to Schedule restart. Choosing to do so gives you a few options as to when to set it.

You can choose to set the restart at any time for days in advance, all you have to do is choose it and save it with the Schedule restart button.

Once you have done so, it will tell you when the restart is going to happen. You can still change it again if you desire.

Your computer will remind you when it's going to restart, giving you options to restart it right there and then, to reschedule, and to dismiss the notification (letting it continue as set)