It depends on what other puzzles you've completed. All I'll say about the boulder is that it will not be moved by any of your villagers and you cannot initiate it. If you have the right "person" on your island, it will happen in it's own time. You just have to be patient.
_________________________
My VV2 story, "A Twist of Fate"
And don't miss Krystal's stories, all three of them!
"Life is too fast... unless you're in traffic."