If landing, after you've picked up your bags. When taking off, when you know you need it. Usually they are on a every half hour schedule.
I called for the shuttle after I landed- I waited about 10 minutes.
You may call for the shuttle at any time. It is a 24/7 on demand service. If you are at the airport ready to be picked up, it takes just a few minutes to get there. Best regards, Andrew
When I was there last, it wasn't available.
Probably an hour ahead if going to the airport, the front desk should have a specific plan.
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