At what age range do Russian university students start their masters degree?

Usually right after they finished their bachelor/engineer degree, since it's usually much easier to enroll to the masters program if you graduated from this uni. But there is no age restriction so it doesn't really matter. Russia has different academic degrees. The soviet one was: engineer (basic uni education, 5 years usually. 6 years for e.g. medicine students, requires diploma paper public defense) -> candidate of science (3 years usually, requires some sort of scientific paper, public defense of it and a number of publications) -> doctor of science (no time limit, you conduct research on your own, requires front-end scientific paper, a certain number of publications and public defense of your work). Now there is a transition to a westernised system: bachelor (4 years) -> magister/master (2 years) -> candidate of science -> doctor of science. Candidate of science and doctor of science are often translated as PhD, which is not entirely correct, since the requirements for the degrees aren't the same.