Happy to report back that it worked! We had a 6:05 reservation and finished up about 7:35. We gave the server our DVC card and the receipt had the "DVC EarlyLate Food" 30% discount. We were also able to use our TIW for the adult beverages.
This was our first time at Jiko, and I have to say O...M...G!! The food was amazing! This may be my new favorite restaurant across the entire WDW resort! My filet was not medium, as requested, but it was tender and flavorful despite that minor shortcoming. The Malva Pudding was so delicious! We have stayed at Jambo many times and have taken a pass on this place. Never again! The 30% wooed me and has turned me into a guaranteed return customer (as long as TIW remains a good deal for us, of course).