Hi there,
Going from memory here, back when I used F1n's daily, Ithink that it was up to the user when the first frame was actually exposed onto the film.
The leader is attached to the take-up spool, shutter fired film wound, shutter fired film wound until it was obvious the film wasn't slipping - back closed - repeat fire/wind until it was felt the film at the shutter was now the unexposed film from the canister. Not a good explanation but I vaguely remember having a procedure of two shots with the back open (to ensure correct take-up) and three shoits once the back was closed - then we assumed the film had *officially* started. When in a hurry this was done in a contiuous movement as a blast on the motor drive. In reality this was a failsafe as we were well into the unexposed film.
Shutter speeds were whatever was set by on the camera or by the auto exposure - there was no over-ride.
Great cameras though.
Sim2