I find that sometimes upgrades are immediately available even if booked a long way in advance, and sometimes they are not released as available until about 2 weeks before the flight. In this, as well as in pricing, they do not seem to reward you for booking well in advance. Often prices are cheaper, for example, 2 months before the flight as opposed to 10 months. If you are booking well in advance, and your dates are a bit flexible, and ring Emirates, they will often tell you if certain dates are currently" showing upgrades as available.