I'm having the same trouble finishing this achievement on PC.
I just don't see any way to turn the achievement on until after the opening scene with Cassandra and Leliana at the gate where the game releases control of the character to the player. Is there a way to turn it on at character creation? If so, I don't see it. And there doesn't seem to be a way to turn on the trial through the options on the home menu either.
I turned Trial of the Fool on immediately after the first cutscene at the Haven gate and played through until Skyhold, reaching level 5 after the Inquisitor hoisting the sword scene. When I didn't get the achievement, I made sure Origin was connected, connected to the internet through the game itself and replayed the Battle of Haven. I reached Skyhold at level 4 this time and no achievement unlocked.
I've tried repairing the game, clearing the cache, restarting the computer and just about anything else that I could think of and nothing works. I can only say it's completely bugged. While playing this game, the Travel Light achievement unlocked with no problems.
Could it be that only one trial at a time can be attempted? Seems a little off if that's true. I finished two trials at the same time in a previous game, Even Ground and Walk Softly.
EDIT: After an all-night download, I completely reinstalled the game. Apparently, my game never completely updated but was still playable after the last patch was applied. The custom levels card now appears in the character creator where it was not visible before. If you have this trouble, I suggest a clean install of the game.
