Fabian:
Thanks for raising this issue. The information in the template is correct for users who have a native date format setting as MM/DD/YYYY in Excel (in other words, US users). I suspect that your native format is DD/MM/YYYY.
You may have noticed that Plan does not yet support international dates in the format of DD/MM/YYYY. We have that on the roadmap. In the interim, we will update the template so that it gives correct directions for those using international date formats.
Best,
Mike
mike.d
Head of BIM 360 Product Management & UX