Hi,
the moving up deadline is part of the application process. When it's reached, the second round of applications is processed (empty spots are re-filled). From that, you usually have about 3 days to set up your attraction at the event.

The final deadline is the first day of the event at the first opening hour. Until then, your attraction needs to be 100% set up.

By the way, for caravans this is similar, just slightly differently: The deadline is the same, but you must have moved your caravans to the fairground until the deadline. You can set them up after the event has started, but you cannot set up caravans that were moved to the fairground after the event has started.

So in case you're running out of time: Set up the attraction first, then your caravan.