Having worked in groundwork’s and construction for a number of years albeit with absolutely zero experience in constructing rides, I can safely say looking at the construction plan that there is “fat” in the plan.
That being said the critical path of the project will be the start of the piling operations scheduled to start month 6 of the project.
If that can be started on plan then the rest will be recoverable. So when that starts will likely be an indication of likely finish time of the project.
Judging by silkstones latest video I would say they are trying to prepare the site for access for the pile driving equipment as soon as possible. But this is but a hunch