When the first 76As came out in 1981 we used to start both engines against the rotor brake. When you released it it was controllable almost immediately. Come the problems with the spindles we then went to one engine start and then released the rotor brake. Offshore with a high and gusty wind blowing we could do a double engine start even though the 76 had sweepback on the tips to stop it picking up the helideck net.
60 knots seems a bit high, the brain cells suggest 45 knots.
It was certainly 60 knots for operating on a deck with an enroute wind of 75.