Upgrade at 5 years at the moment
My neighbour is starting his training early next month. That'll be exactly 5 years to the date since he joined EK. When he joined, he asked the questions you're asking and was told 3 years. So be careful of the decisions you want to make based on what you're told today as it could easily change tomorrow. As long as you accept that things in this industry is largely based on supply and demand, then you won't be too disappointed further down the road when you're told to wait a few more years for your upgrade.
Hope that helps and good luck with whatever decision you make.