Quiet hours: when messages don't send

Cronenta only sends automatic messages between 10am and 7pm, in your own local time. Nothing goes out to a client late at night or early in the morning.

That window itself isn’t something you adjust. What you do control is your timezone, under Settings → Timezone. Cronenta converts 10am–7pm into your local time from whatever you have set there, so getting your timezone right is what keeps quiet hours actually quiet for you.