While I have no experience with the Futura boards, from what I understand about their design and projected use, I will estimate the planing thresholds with a 7.5 sail:
I am 80kg and have been winsurfing for 24 years on all types equipment.
1. F111 = 12-14 knots
2. F122 = 11-13 knots
3. F133 = 10-12 knots
This assumes that you have good pumping skills. The difference in pumping or not pumping is about 2-4 knots of wind, meaning that if the wind can push you up on plane with no pumping in 14 knots, then with pumping, you could possibly get on plane in 10-12knots.
The above estimates are in the ball park, but certainly could be up for debate. There are lots of variables that impact planing - fresh or salt water / board design / sailor skill / sailor weight / sail design / water state (flat - choppy) / direction of chop / steady or variable winds & fin size.
"Direction of chop" means that if the chop is NOT running directly in line with the wind, which is pretty common on fresh water lakes, it is easier to plane heading into the chop than running with it. When the chop turns in to bigger waves, then just the opposite can be true (pump to surf down the swell to gain speed and plane).
Hope this helps,