Hello mduraphe
What a relief! I am happy SBB helped you out.
You are not in a hurry. You do not have to purchase the passes now, it is totally fine to get them a day before arrival. They do not sell out nor is the cost raising.
Personally, I wondered if we could make, as part of a user experience improvement, the start date a mandatory field, to be completed manually. From my experience, there are too many tourists having the same issue. It generates extra work at both ends.
Kind regards,
Roland
@Nicole_B