Do Not Disturb for specific duration in Samsung S8 Quick Settings
I can see in Google's documentation for the Pixel that the feature that lets you set how long DND mode should last (15,30,60.. minutes) is there in the Pixel, just as it was in my old Sony Xperia:
https://support.google.com/pixelphone/answer/6111295?hl=en

Unfortunately it looks like Samsung removed this feature with their Touchwiz overlay, so you're only left with scheduling DND between specific times or enabling it forever.

To bring back this feature I ended up having to install an app: https://play.google.com/store/apps/details?id=com.cabooze.buzzoff&amp;hl=en