I've said this for many years. Those FO's who talk about upgrade and can't decide CRJ or E-Jet are not ready to upgrade. Most of their heads have been stuck up their .... and they haven't been paying attention to learning in the right seat. The FO's who tell me they don't think they are ready, asking me all sorts of questions, wanting feedback, are ready. They get it. You will never know everything and be perfect as a Captain. You just do the best you can.