I think that's about right, Unregistered.
Perhaps 9 knots if you pump a bit to get going.
I manage from 8 knots and a 10.9 without any pumping.
Just point a bit downwind and off it goes. Keep your leggs straight max tension on the harness lines. The fin starts working. Choose the exact moment to move your feet backwards, then enter the footstraps and feel the acceleration. Luff up when you have enough speed. That's planing without a white cap in sight. Wonderful !