The first documented use was in the Disney TV movie Johnny Tsunami (1999), according to most Internet sources I’ve looked at.

It’s actual usage was much earlier than that. I well remember we were using “go big” and “go big or go home” in London in the mid-1980s, and we (certainly I) picked it up from older American exchange students (also Californian surfers) then. So that might be a clue.

It is military expression used by pilots involved in bombing targets. It means the longer you stay on the target the high probability of a direct hit. The go big means to expose your aircraft to ground fire for a longer time period to insure a direct hit. The go home means if you haven’t the intestinal fortitude to go big just tuck your tail and go home.