Indeed the stamping will have to continue until at least 90 days past the point when an undisclosed "high percentage" figure is reached, otherwise there is the possibility of inconsistencies on the 90/180 rule. Due to the situation in Portugal, this can't be until about August, as things stand. That said, even if you do not use a kiosk, you may well be on the EES database, so it's not the kiosk that's the decider here.