Just curious what my current pace works out to!

I’m burning my first items here at level 21 (items like 山, 十), where does that put me in terms of pacing?

Assuming there’s one item you never got wrong on Level 1 (and did all reviews for on time) it would take about 173 days to burn said item. If you’re on level 20 now, you’re paced to finish in about 519 days total.

There are about 15 or so “fast” levels, so the math is a bit harder than that.

If you burned your first item by the time you got to level 21, that means you completed 20 levels, 2 of which were fast. Since the burn time is about 173 days as ryan said, that means you complete a level in about 173 / (18 + 2 * 0.5) = 9.1 days per level. Since at max speed a level is 7 days-ish per, that puts you at decently close to that. I’d say you finish in roughly 9-10 months if you keep that up.