This page explains what happens between arming a cue and starting it. There is nothing to set here. The page describes behaviour that you will notice, and that you could otherwise mistake for a fault.
What the program does
The program prepares the armed cue in advance. As soon as a cue turns green, the program loads the web page, builds the scene, or opens the media file and moves to the in point. It then keeps the cue ready, so that the picture appears immediately when you press GO.
After every GO, the list arms the next cue automatically. This means that the next cue has usually been ready for some time when you press the button again.
What you notice
In most cases, you notice nothing. The difference is only visible with a web page cue: a page that was armed a few seconds ago appears instantly, but a page that you arm and start in the same second may still be loading.
What is not prepared
A media cue does not play in the preview, so a clip cannot reach the output by accident. Video and audio run only when they are live, and not when a cue is selected or armed. An armed clip waits on its first frame in the next-cue picture beside the preview, and the preview and the output keep showing what is on air until you press GO.
A countdown in a scene does not run until the cue goes live. The clock therefore starts when the audience sees it, and not when you arm the cue.
Practical advice
Give the program time to prepare. Arm the next cue as soon as the current cue is running, and not at the moment you need it. In a normal list, the program arms the next cue automatically, so you do not need to do anything.