My money is still on by the end of summer, track will be complete. Possibly before that. The track will start flying in very soon, not much left in terms of footer work, it is all nearly there. The pipes that can be seen pouring the concrete is one of the final stages of building / re enforcing footers.
From what I am hearing, the wetter than usual spring we've had, has pushed footer work behind schedule slightly. Not helped by the fact some of said footers are at the bottom of a pit where water collects and where the ground will be the wettest after rain fall. If you've seen the site, you'll have seen how wet is has been recently. The upside of said delay though, means there will be a stockpile of track onsite for when they are ready with the footers. Meaning they can just crack on. These delays are all factored into the timeline anyway, so nothing to worry about. They are keen to get the track in ASAP, as there is alot of other work, some time consuming, that needs to take place, non of which can take place until the track is in and the heavy plant out of the way.
Make of this what you will and take it with a pinch of salt, but I am also hearing that the waterfalls will be returning, in what capacity I do not know. But they will apparently be back. There is no point doing anything to those though, until you have the new footers in at a minimum.