Why do u think Taka Nuva came later then the other Toa?
Here's what I think: The Toa were in those canisters to go to Mata-Nui but Makuta knew Taka was powerful & the leader. So he went into the sea & got Taka back on his old island. When Taka got out he tought it was Mata-Nui, so he stayed there 4 while & then realized it wasn't. So he had to go in his canister all over again & then got 2 Mata-Nui.

Actually, We are pretty sure that Takanuva has been on Mata Nui the whole time, just in a state of rest. When Takua finds the Mask of Light, they have to find Takanuva and give him his mask.