I think it may be earlier than that, in 1960, as I've just been flicking through my "Tour de France - The Story of The World's Greatest Cycle Race" Book and in all the pics up to 1959 alll the bikes appear to have a pump, but from 1961 on (no 1960 pics strangely?) I can't see any pumps fitted.
They may of course have been voluntary from then on, as a lot of the bikes, post 1960, on Finney's link above, still appear to have pump fittings.
Steve.