As someone who went 200 attempts before finally making it much more than 10m from the dock, I will second the make it easy with a big foil advice. That said, not all big foils are the same.
I did 100+ attempts on an old style thick surf foil with a 1m span and 1900cm2 area, AR of 5 or somethint like that. Even with a good long, low dock the foil could stick out under just no luck. Biggest issue was the roll-yaw coupling from the massive anhedral that foil had. Instand speed loss from lack of anything resembling glide killed the few bobble free starts I managed in just a couple of pumps. Got rid of that foil and dropped dock starts for a couple years.
Started again this spring with a 1500cm2 foil of 6 AR, but thin and 95cm span. Much better than the above foil as it is very flat and so minimal roll-yaw coupling. Still a lot of blown starts and bobbles as the foil is so loose in roll. Made progress but just couldnt keep the speed up to go more than 5 or 6 pumps before stalling out.
After 50 or so attempts I buckled and bought a dockstart/pumping specific foil, also of 1500cm2 but 116cm span, 9.2 AR and a liftier section. About 50 attempts and I just cracked the 100m mark for the first time yesterday. So much easier due to the glide, low stall speed, and stiffness in roll.
Fitness now finally becoming relevant to my pump game. Probably 2min of pump time yesterday and I am fairly cooked today. Thank you @wenis for sharing, so reasuring to hear I am not the only one finding this demanding!
Edit: 41yrs and about 97kg in my summer suit.