It doesn't say in any of the Vampire Academy books when Dimitri's birthday is.
Dimitri Kitsikis was born on June 2, 1935.
Dimitri Yachvili was born on September 19, 1980.
Dimitri Pisarev was born on October 14, 1840.
Dimitri Champion was born on September 6, 1983.
Dimitri Terzakis was born on March 12, 1938.
Dimitri Tiomkin was born on May 10, 1899.
Prince Dimitri Romanov was born on March 4, 1926.
He died February 2, 1907 (Gregorian calendar), 6 days before his 73th birthday.
Dimitri Bilov is 182 cm.
Dimitri Leonidas's birth name is Dimitri Leonidas.
Dimitri Romanoff's birth name is Dimitri Theodore Romanoff.
Dimitri Tiomkin's birth name is Dimitri Zinovievich Tiomkin.