The firmware has never supported master valve operation on a per-program basis — it has always been on a per-valve basis. What you quoted is from an early post and that has never been implemented.
In any case, you can set master operation flag for each station/valve individually. Check the firmware tutorial video, or the user manual for details.
You are right that the master cannot be set to open before other valves. Usually turning on valve is not a problem, and the valve doesn’t require pressure to turn on. In fact, having the master valve on before other valves turn on can produce water throttling issues. Turning off valve, on the other hand, does require certain water pressure. This is how typical sprinkler valves work. If you do want to turn on master before other valves, here is a workaround:
1. create a dummy station, and make sure this is the first non-master station
2. set the dummy station to activate master
3. in your program, set the dummy station to run for whatever time you need
Since the dummy station doesn’t actually turn on any valve, this basically achieves turning on master before any (real) valve turns on.