I've been reading Sergio Meda's book entitled COLNAGO and put this time line together trying to piece together some key dates of early, 1950-1969, Colnago built bikes. In the book there are these references:
1950/1951 pg. 24 "let's make it clear that the bike he used was not a bought one. He had made it himself and it had Colnago Ernesto stamped on it."
date not specified pg. 27 "first Colnago model came out under the name La Freccia" (the arrow).
1960 (approximately) pg. 27 "first foreign customer, "let's say 1960", was from Berkeley, California"
1970: Colnago created the flower/club logo after the Dancelli win in Milan-San Remo. This would indicate that the playing card with club logo's cannot be earlier than 1970 although they are often listed as 1969.
1964 thru 1973: pg. 29 "at Molteni he is already offical supplier: the bikes are called MOLTENI by express wishes of the owner but they are obviously Colnago's".
Below: "Super Freccia" decaling attributed to 1959, courtesy of Ken Denny (Super is above COLNAGO, Freccia below); currently owned by Greg Softley in Australia