So typically how long (hours on task and elapsed years) is typical for an SO to progress to an FO and for an FO to progress to a Captain?
That's a bit of a magic question, that all SOs wish they could answer.
But, in a static and stable environment (in which retirements aren't being distorted by extensions to the age, and the fleet is neither growing or shrinking), and given the current makeup of the fleet, the numbers in each rank are approximately equal (there are more SOs than Captains or FOs on the big jets, but they don't exist on the smaller ones). In this situation the average career will have time in each rank equivalent to the relative percentage of people in each rank...i.e. if there are a third in each rank, then you'll spend a third of your time in each rank. So, if the average career is 30 years, then 10 in each rank.
Historically, the longest times were around the time of the introduction of the 747, when the much smaller 707 was replaced with a much larger aircraft. Around then, the times blew out to 15 years as a SO. But, these same people then had their FO time coincide with the introduction of the 767, and most spent only a couple of years as FOs, and then they got the bonus of having the captains in from of them retire at initially 55, then 57, whilst they got to go to 60 and now 65. There are even some 8 year captains, although they have just about mythical status. Just have to be in the right place, at the right time, with all off the right boxes ticked.
Fleet growth leads to shorter times, and contraction to massively longer. Currently SOs see little chance for promotion ever, as they need Captains to die before any slots will become available. In my career, I have never seen so many junior pilots actively looking at alternative airlines (and none will consider the 'Qantas' group). If, as some expect, QF decides that no current QANTAS pilots are to fly the 787, then we'll see demotions and retrenchments on a massive scale. On the other hand, Emirates, Qatar, etc, will have little trouble recruiting well trained and qualified people.