Who were the first female judo players? When did they train?
Keiko Fukuda was promoted to fifth degree in 1953
Takako Kunigoshi is a possibility; she started training in 1933.Edith Margaret Garrud started studying Judo in 1899; combine that with Dr. Liepmann's answer below, and it appears that women started studying Judo in both Japan and Europe at about the same time, which is somewhat surprising.
According to "just another judo page", the first woman judoka was Sueko Ashiya, who started training in 1893, which (if true) would be 11 years after the official founding date of the art:
No further reference is given. A direct inquiry to the generally fastidious records-keepers at the Kodokan seems called for to achieve a definitive answer.
Note that women's judo was highly modified, with more emphasis on kata and less on shiai. Women were not allowed to compete in the world championships until 1980, after protracted agitating.