Big Boss is a lot like Father Christmas: he sneaks into your home unseen; he has toys made by special helpers far away; and you want to slide down the stairs when you wake up after his visit so you can see as quickly a possible what he's brought you.
Alas, Metal Gear Solid V: The Phantom Pain [official site] will not have a pre-load option on PC so you'll need to wait. However, thanks to timezone trickery, pre-orderers should be able to start downloading and playing a few hours before its official release.
What he's saying, I believe, is that though the game doesn't officially launch until 10am Pacific time on September 1st, folks who have pre-ordered it will be able to start downloading as soon as it turns September 1st in New Zealand. That'll be 1pm on August 31st in the UK, and these times in other zones. He adds that it'll be 28GB to download, so when exactly you'll get to play depends on your connection, but you could theoretically start playing before the general populace of consoleers.
"Never pre-order," I've told you, knowing full well that I'll probably cave and throw cash at Konami so I can start playing The Phantom Pain as soon as possible. Look, I already explained my expanded reasoning. After waiting to see the state of Ground Zeroes, I think I may be okay with pre-ordering The Phantom Pain. Maybe. I haven't yet.