Just starting and I already have a question

I received my Arwen yarn yesterday. Yipee! I'm using Cascade 220; lavendar heather; colour 2422. I cast on right away and I'm half done the back already.

I have a question about the sleeves. I noticed that there is only one sleeve width (13.5") for all sizes. I have *ahem* chunky upper arms and 13.5" is way too small. I need at least 15" to get my arm in plus ease. Do you think it's ok to start the sleeve a little earlier and do extra short rows?

One other sleeve comment... I noticed that the cuff is 10". I wrapped 10" of tape measure around my average sized wrist and it seems really big. The picture shows a much snugger fit. Do you think the model has huge wrists?