I want to give a guest pass to my friend so he can roll some Nuclear Dawn with me this weekend, but when should I send it? If I give it to him now (Wednesday), will the 3-day clock start ticking immediately (if done direct to a Steam account), or does he need to do some activation? Can he "pre-load" it before the timer starts?
The person is unable to download the game until after they receive the 3 day pass. By receiving the pass, they can download the game and can play the game after the download (and any subsequent patching) is done. The timer starts the moment they choose to activate the pass, so it would be best to let the game download overnight if they have a slow computer and plan to play all day the following day.
I took a look at forums that ask your question and it looks like it starts when they download the game from the guest pass. Hope you enjoy playing!