ّFrom when La (A)= 440 Hz? and who did it?

Answer 1

I don't know if I am quite accurate, but will try and do my best. Before pianos were built the way we know them, they started out life as a harpsichord, clavichord or cembalo. These instruments used feather quills to pluck at the strings inside the box, and sounded pretty much like a big acoustical guitar. The strings were made of gut, like violin strings of the day, and stretched in warm weather, going out of tune fairly often. Wealthy people ( like the princes and kinglets of the early Holy Roman Empire in Germany) who had two or more instruments, often found that no one note ever matched. In 1722, Johann Sebastian Bach's work, The Well-tempered Clavier (Das Wohltemprierte Klavier) was written for an instrument that could and did stay in tune in a way so that every note was in tune in every key played on it. So the idea of a standard tempering or tuning happened in the early 1700s.
With time and experimentation, this gentle sounding instrument gradually took on a different sound. Beethoven's "piano" music was written for a "hammerklavier", where felt covered hammers took the place of the feather quills, and the strings became metal.
We also know that the acoustics of the time of Classical and early Romantic music were softer than now, because of the relative scarcity of metal ( except horns, trumpets, etc) in instrument making.
One of the first standard tunings for an orchestra is recorded by the London orchestra of 1828, where the A was set at 435 Hz.
In 1932, A 440 was recognized as "the" standard tuning by all American piano makers, and probably by the Europeans as well, and has been used as such since then. ( although several European orchestras do tune A443 to 445 for a more brilliant sound)

Answer 2

JS Bach...He also implemented the thumb in playing on the keyboard.