I think this adage is very old and has been rephrased countless times (though with slight modifications), but the modern English adaption might be from the 20th century:
King Wuling, "A talent for following the ways of yesterday is not sufficient to improve the world of today." [Warring States Period]
Lieut. Col. J. L. Schley, "It has been ...
The earliest reference I could find is Christoph von Tiedemann on p. 42 of Persönliche Erinnerungen an den Fürsten Bismarck (S. Hirze, 1898, link) based on a 1897 talk:
"ich habe nicht schlafen können, ich habe die ganze Nacht gehaßt", sagte er mir eines Morgens
Von Tiedemann knew von Bismarck personally and spent a lot of time with him. The ...
Note that this answer was written before "Update 2" in the question appeared.
It seems to be an anecdote, reported only one single time, as "he once said", by one source, undated. It is of a singular nature, not repeating. In that single source it has no relation to any specific occasion and is even phrased with ambiguity, ...
The Yale Book of Quotations (edited by Fred R. Shapiro) mentions several quotations related to that one. The most likely inspiration for Kennedy's line seems to be the following passage from Khalil Gibran's 1925 essay "The New Frontier":
Are you a politician asking what your country can do for you or a zealous one asking what you can do for your country? ...
Another point against the authenticity of the quote: The date of the speech is given as 2 February 1835. However, there was in fact no Parliament on that date; it had been dissolved on 29 December 1834, triggering the 1835 General Election, and was not summoned again until 19 February 1835. Here is the relevant page of Hansard.
Bismarck is very famous for his quotes, but even the Otto-von-Bismarck-Stiftung has no complete summary of them (at least online).
Asking them would be your best option for a reliable result, since his quotes are often used out of the original context.
This looks pretty much like a conflation of the type already mentioned in comments:
Are you, perhaps, thinking of Samuel Johnson's dictionary, where he described oats as: "a grain, which in England is generally given to horses, but in Scotland supports the people"?
A few indicators to support this assumption:
Such description is ...
'On s'engage partout, et puis l'on voit' appears in Literarisches Wochenblatt, Volume 3 - but not attrbuted to Napoleon, though he is twice mentioned in the short article. So we are now back to 1819, in Napoleon's lifetime. Perhaps this is a proverb rather than a quotation?
I vote for Cecil Rhodes.
First, the author, William Bolitho Ryall was a South African, as was Rhodes.
Second, Rhodes was mightier than most of the others, insofar as he had a (former) country, "Rhodesia" named after him. (Alexander the Great "only" had cities like Alexandria named after him; Napoleon, "nothing".) Although technically just a wealthy private ...
There is a more subtle tragedy that waits for adventurers than ruin,
penurious old age, rags, contempt. It is that he is doomed
to cease to be an adventurer. The law of his morphology is
that, setting out a butterfly, he is condemned when his
development is ripe to become a caterpillar. The vocation of adventure is as
tragic as that of Youth ; its ...
A summery from some of the comments, which may be interesting to others:
The Inauguration of John F. Kennedy - Wikipedia says This appears to be an elegant rephrasing of Franklin D. Roosevelt's acceptance speech at the 1936 Democratic National Convention :
"To some generations much is given. Of other generations much is expected. This generation of ...
If we count statements made about previous generations, these go back to some of the oldest literature. There’s a speech like this in The Iliad, set in the mouth of an ancient character of the epic, about how much greater an earlier generation was and young men should be more respectful to their elders. You could read this as Homer saying that old men have ...
It seems very plausible to attach his quip to Lenin, as the Red October and its aftermath was practically exactly that: take action and see what comes out of it.
It seems very strange to attribute this 'motto' to Napoleon who is often portrayed as far more into planning and strategy and tactics. Well, for most of his career. The beginnings might be a little ...