I brewed a Duvel clone using this yeast, the WL version, which I pitched a smaller starter than yours and added the sugars at the end of the boil. I also ramped up the temps to 82 degrees over the first week.
That said, after 7 days,the brew wasn't even close to finished. It took an additional two weeks to finish out. My FG dropped to about 1.007.
Be patient and keep it in the 80's...it should finish. FWIW, I read another post recently that this yeast is not a quick finisher...wish I knew that to before brewing.
This beer turned out awesome BTW!!! Yours should too!