There is no minimum requirement, and that is not meant to be disrespectful!
We actually hired a FA that had zero experience, trained her to our standards, as well sent her to FA initial at FS, and Culinary School at CIA. The reason we did this is, unlike so many FA's that already had experience, she was enthusiastic to have the job, took the job seriously and has since become one of the best FA's we have ever had!!
I would do it over and over again with the right person!
This is our model, but I am sure some will find some reason to bash it. However the owner loves her, so at the end of the day, thats all that matters!
J