yes, and to clarify: the question from me was WHEN the FIRST 90 days report must take place: 90 days after the start of extension, or already when the single visa is extended to a 1 year visa.
Well, a one year extension was issued based on the single entry non-O, and then I thought indeed that my first 90 days reporting should be 90 days from the date the extension as issued.
Thanks for the input! (yes, this was done by an agent). So, in conclusion, in normal conditions the first 90 days reporting takes place around the date which is 90 days from the date when the single entry non-O visa is extended to a one year visa?