how do i know when safe to move to new tank?

I am moving from a 16g tank to a 40g tank. i have new live sand and new live rock and new saltwater running in 40g for 1 week plus 2 scoops of sand from old tank. How do i know when it is safe to move corals and fish to new tank? If i have to "cycle" it first, how do i do that? I don't want to sacrifice my fish. How do i know if the tank has already cycled? help please!



thanks