I do see your point, LittleMo, since Queen Consort (like First Lady) is not an official government position. But I think Queen Elizabeth became Queen Consort when her husband became King, just because she was married to him. The anointing of the monarch is a sacramental moment and the oath and crowning are official moments which confirm the accession of the monarch. I don't remember anyone wearing a crown before being crowned. At some point, the Diamond Diadem stopped being a consort tiara and reverted to its monarchical role. It seems to stand in for the crown during the approach to official events, including the coronation of a monarch, and of course identifies the Queen on official documents like stamps and money.

Edit: Someone is sure to point out that Queen Elizabeth (QM) acted as a Councillor of State and conducted investitures, like other members of the royal family. But she did not have the constitutional authority of the monarch, though she was his confidant.