As mentioned yesterday, a number of chronologists place MISS in December of 1896 or 1897, despite Watson’s own statement that it took place in February.
Based on that, we take this from A Day by Day Chronology of Mr. Sherlock Holmes according to Zeisler and Christ, compiled by William S Dorn, BSI, DWNP:
December 8, 1896: Holmes visited Dr. Leslie Armstrong [MISS]
It argues the degree in which I had lost touch with my profession that the name of Leslie Armstrong was unknown to me. Now I am aware that he is not only one of the heads of the medical school of the University, but a thinker of European reputation in more than one branch of science. Yet even without knowing his brilliant record one could not fail to be impressed by a mere glance at the man – the square, massive face, the brooding eyes under the thatched brows, and the granite moulding of the inflexible jaw. A man of deep character, a man with an alert mind, grim, ascetic, self-contained, formidable – so I read Dr. Leslie Armstrong. He held my friend’s card in his hand, and he looked up with no very pleased expression upon his dour features.
‘I have heard your name, Mr. Sherlock Holmes, and I am aware of your profession, one of which I by no means approve.’
‘In that, doctor, you will find yourself in agreement with every criminal in the country,’ said my friend quietly.
[MISS – Sherlock Holmes: The Ultimate Collection. Maplewood Books, Kindle Edition]