well he was Fighting for the Mandalorian Wars for at least 40 years (he admits this in Kotor 1 in his backstory to Revan)
So an average age of a beginning normal fighting age for a career solider like Canderous is 18-20 when they start.
With the Mandalorian, Boot camp is from the birth until they can serve as a normal Mandalorian solider.
So it will be normal to assume that Canderous is about 60.
If you are a successful career solider, you can become an officer.
From Kotor 1 Canderous' backstory, he was a high ranking Officer in the Mandalorian Military because he admits in planning many major victories in the Mandolarian Wars.