Thanx for your replies!
I tried it yesterday with straps and it was not good for me as i kitefoil strapless since 5 years. "Pulling" the board didn't bring me earlier on the foil, maybe my fault. And i didn't like the feeling of "locked" feet!
Back to the beach i dismounted the straps and tried not only to stomp while pumping, also to push it a bit forward with the backfoot. That worked good for me. I stay strapless;)