Step 21: Realize before attempting this step that there's a missing step between 20 and 21. It's effectively the same as step 13. Step 22 and later should be delayed until the shelf is moved into position with the exception of steps 32 (which is where I've stopped for tonight) and probably 33 which should be done before then.
Bad instructions aside, it's going together fine and is looking pretty good in its almost finished state. Looking forward to putting stuff on the shelves.