The amount of time required to get your crew commanding qualification (I will explain why I highlighted this in a second....) has varied (in my experience) from about 4 or 5 years (about 20 years ago) to about 15 years (about 5 years ago) to about 7 or 8 years now (all are based "on average" years of service.... there have always been "streamers" (guys who move up fast) and then there are the guys whose careers took the more scenic route (to be polite to those who don't fall into the first category)).
'Back in the day....' there were guys who got to crew command well before they were ever officially qualified (and/or ready). This, in my opinion, was criminal (on part of the "system"). Why?? you ask. Before anybody is allowed to push a squeegee in the military they have to be thoroughly taught, assessed, retaught if neccesary, and then the paperwork sent to the proper authority... (I'm exaggerating here, but to prove the point that the military is prone to excessive hand holding for even commonplace tasks). However, in the past, people were allowed to crew command vehicles before they were ever qualified/taught, mostly due to lack of qualified personnel, and there was a lot of trial and error involved. If a soldier was lucky, they received quality mentoring from an experienced crew commander. Usually the soldier would be the loader (in a tank) or the gunner (in a Cougar or Coyote), and the crew commander would take the time to explain what was being done (i.e Crew Commander's Appreciation, a GOOD set of orders during Battle Procedure, etc) and then allowed the junior soldier to take over and crew command the vehicle under their tutleage. However, I would argue that this happened less than most people would like to admit, and many pers weren't adequately trained. And, inevitably, a lot of killed and injured soldiers resulted. This wasn't limited to the Armour Corps, and I would argue that, as a Corps, we did a fairly good job, whether by luck or by osmosis (learning from what was going on around us), but as we became more mechanized, especially with the advent of the AVGP family and LAVIII/Coyote, turreted vehicles especially, there were more and more high profile accidents.
Which brings us to modern times: before a soldier can crew command a vehicle (in the Armour Corps: I'm not 100% sure where the other Arms are in regards to training/employing commanders for their vehicles), they must have the proper training, and receive the qualification. There have been a few interim measures, the most familiar being the AVAMS (Armour Veh Administrative Movement Specialist(?)) Course, which was geared at getting echelon pers and support trades pers the skills needed to move (non-turreted) Armour vehicles around adminstratively (i.e. not tactical cross country movement). At the Armour School, the student s on the Armour Recce Crew Commanders Course (ARCC) are now generally young MCpl's or senior Corporals, whereas when I did my 6A (in 02), we were all pretty much senior (average 6 years in rank, and 15 years in) MCpl's , ready for promotion to Sgt. Most of us had been crew commanding for some time, many having crew commanded on deployments overseas. Then we had the honour of doing the course, and then being told that we were now qualified to crew command a vehicle. Kinda bass-ackward, dontcha think?!?!?
Anyway, the moral of the story is this: once you have done the requisite time in the various crew positions (driver or gunner (of either tank or recce vehicle), operator (recce veh) or loader (of tank)), you will have received your PLQ (Primary Leadership Qualification), and then be slated to take the ARCC (and then the Direct Fire (DF) portion if you are on tanks (I would love to say "only if you are a Strathcona", but I suspect that the tanks aren't going to be exclusive to only the "Army of the West" due to recent events.... you heard it here first!!! [Disclaimer: This is only wild speculation on my part, but watch the news, do the math, and you may come to a similar conclusion....]). I suspect that the average time for this to occur in the not-too-distant future will be about 4 or 5 years of time in. Again, this is speculation on my part, but again, look at the attrition rate, huge recruiting numbers, and it's starting to look a whole lot like the mid-to-late 80's again. I predict one-hook troopers on PLQ's in the near future, if it hasn't already started happening (I'm talking Reg Force here people: don't tell me about the one banana Reservists that stole your PLQ position, disgruntled CFLs (Corporals For Life).... I better start being nice to the recruits around here: at the rate that things are going, they might be my boss before I retire!!!
Hope that helped,
Al