Hello Jeff,
An expected time to stay at the rank of 2nd lieutenant in the greek army would be 3 years. However, in wartime period, being promoted for bravery was also possible.
As opposed to the US system, an NCO would eventually become an officer, after about 10 to 15 years I would say.
There are also the reserve officers who are normal conscript soldiers who get officer's training and they used to become officers after 2 years (2nd Lt).
If you have any specific questions, you are wwelcome to contact me with PM.