Count back from your departure time
For European flights it's usually recommended to be at Schiphol about two hours before departure. For intercontinental flights, three hours is a safe guideline, especially if you need to check in luggage.
Add your parking time on top of that. With valet parking you drive straight to the departure hall; allow roughly fifteen minutes extra for arrival, handover and inspection. With shuttle parking, allow more time, since you park at our site and then take the shuttle to the terminal.
During holiday periods, early morning flights and rush hour, extra margin is sensible. On the day of travel, always check the current traffic situation and the instructions in your parking confirmation.
Example European flight
Departure at 10:00. Make sure you're in the terminal around 08:00. With valet, plan the handover around 07:45.
Example long-haul flight
Departure at 13:00. Make sure you're in the terminal around 10:00. With shuttle, plan your arrival at the parking site around 09:30.