How does the 90/180 day rule work if my 90 day cycle does not restart until 29th March but my biometrics is dated the same day?

Perhaps I am needlessly confused but I’m a British passport holder who has been spending time in Portugal as a tourist while I wait for my GV biometics appt.

I have not overstayed in anyway but I’m confused on the exact protocol with regards to re-entering the country legally (and subsequently traveling in other EU countries afterwards) with regards to my upcoming appt which is scheduled 29th March, basically the same day as my new period of 90/180 days begins.

To be precise, I would obviously prefer to be in Portugal at least a few days (and ideally even a week) prior to my appt because I do not want to miss it / jeopardize this meeting in any way due to flight delays / cancellations etc.

Can anyone explain the ramifications of entering Portugal (and thus the EU) 1-2 weeks earlier than my next ‘allowed’ stint of 90 days? I calculated my past days using the Schengen calculator and according to this, I’m not supposed to re-enter until 29th March.

I understand that if I have a biometrics appt with a letter confirming this, then I’ll be able to attend the appt regardless of the 90/180 rule, but my specific question is the issues I might face for some planned trips to Spain to celebrate a family member’s 60th wedding anniversary in May. My plan was to fly to Barcelona from Portugal for 4 days.

If someone can advise on this issue, I’d be grateful. I’ve attached an image of my recent dates in and out of the EU (all of the time was spent Portugal apart from 4 days).

I can only tell you that my attorney told me I would need to show SEF I was present “legally” at the time of my appt. She offered that advice because I was spending a few months in Lisbon. When I asked her if she meant I hadnt overstayed my 90 days, she answered “yes.” They take your passport for examination at the appt. so presumably a clerk could be looking at that.

That having been said I have a friend living in Lisbon for a couple years now and he is awaiting his appt but has been told by his attorney its not an issue. Do you have an attorney you can ask?