Hello! I commented about this on the Reddit board earlier. My so-far only Ironsworn game had me house-rule that I'd completed my quest because I hadn't understood what a proper unit of progress was. (Escort a guy to a grove and back; probably should've treated getting there and other steps as progress. So I'm no expert.) If you're introducing this system to new players you might want to say outright what kind of things should trigger quest progress.
About the clocks specifically... I like that you're reducing the vow/quest levels from 5 to 4 and not having an absurdly high Epic level. I still feel that having four dials like that might puzzle new players though. Is there some way you could express the idea with a single dial? I'm imagining a 20-box track with marks at the 5/10/15/20 levels where the player fills in 1 box every time and works toward a specific number -- but that doesn't properly express the idea that you can try to win early, with risk. If you really like the dials, what if you tried having one dial with 3 little checkboxes beside it? Then your rule could be like, "each time this clock fills, mark one box. When you have [quest level] boxes filled, then you can make a win-quest roll and pay attention to the numbers on the clock." Mechanically I think that would be almost the same, and it would take up less space on the page and maybe be easier to understand.