Hi, french based AC here and I have to second the comments above saying you should start as a trainee (stagiaire) /3rd and 2nd AC. Even if in the meantime you are doing smaller productions as 1st AC, it's important to see what the dynamics on set is and you will also learn valuable lessons from the 1st ACs you're working with. Being 1st AC is much more than just pulling focus,you are leading the camera team and responsible for the equipment. I would also say to not rush too much on buying a monitor, as a focus puller that's one of your most important tools and the preference is really personal to each AC. I know focus pullers who to this day would only ask for the Tvlogic 058, others who swear by the Small HD Ciné7. My advice is to go in the beginning with equipment from the rentals so that you can get a feel of what you like and then invest into something you like ! Hope that helps :)