I made a second pair of these. Came out lovely :)

If you are knitting to gauge (41 rows= 4”) you start the thumb gusset shaping at 5” on the fourth row of the fifth lace pattern repeat (41rows/4” x 5”= 51.25 rows) and you will end at the end of the sixth lace pattern repeat.
Therefor I will do a total of seven lace repeats.

Working on these as a store sample, so I actually only use one skein for one mitt.
I noticed an error in the instructions handout #1250. The written lace pattern is OK and the chart is OK, too, but the stitch key is incorrect. The symbols for sssk and k3tog are incorrectly labeled. I realized the hard way as I just followed it without thinking and had to undo the first row of the lace. This is corrected in the errata, but I want to mention it in case you are like me and don’t check for errata first
The yarn is beautiful to work with, oh so soft on your hands (especially compared to the hemp I am knitting with at home right now; making a hemp ponchette).