Maybe if the shutter is already cocked you may have the fire it first.BTW, you must pass the film under the first roller on the 3.5F to make the automatic feature work. So, load your film into the empty chamber, pull the leader under the roller, attach to the take up spool and just advance enough to check that it firmly attached...close the back and keep advancing (you will feel a slight resistance) until the camera locks at frame 1.
Enjoy the Rollei, a very fine camera!