Does God always reveal future things before they happen?
No, God does not always reveal future things before they happen. He can reveal events in His own time, yet often in the Old Testament He prophetically reveals them beforehand—such as naming Osiris, King of Persia, 150 years before his birth. So revelation comes according to His timing, not a fixed rule.
Les explains that when God spoke of Osiris, the King of Persia, He named him 150 years before he was born, and that is prophecy. Whenever the text is in the future tense—'I will'—that is prophecy. Les teaches that God can reveal it in His own time, but often in the Old Testament He reveals things prophetically before they happen. So you have both to cope with. In Exodus 19, God prophetically tells Israel that if they obey His covenants, they can be a treasure above all nations, a kingdom of priests, a holy nation, because the earth is His. That shows God revealing future plans ahead of time, yet according to His own timing.