Think it was around Jan 10th. Fantasmic, Mark Twain, Columbia, Canoes, and DL Railroad are all down for SW Land reconfiguration, Big Thunder BBQ and the petting zoo are now Disneyland History.
If I had to guess I'd say sometime in 2018. But I don't think anybody really knows for sure. Anytime you undertake a big construction project lots of issues can come up and delay things.