Hello. We are looking at buying a 7 days/1 month global pass. The eurostar will be part of our trip. I understand you should book this as early as possible and can do so up to 180 days in advance. If we reserve our seats at the earliest possible time (180 days before travel), will that start our 1 month time limit? Or will the pass start when we actually take our journey on the eurostar itself? Many thanks.