The plans are ready.
They need the ashes of a sacrificed perfect red heifer to sanctify the workers.
They’ve got 2 candidates for that.
Not sure if they have been sacrificed yet.
They need access to the Temple Mount.
There’s room for the temple if they leave off the outer courts.
I believe they could build one very quickly. Maybe in 3.5 years.
A treaty Will have to be the trigger that allows them access to build it.