After an introductory course in logic (propositional and predicate calculus) and the article on the SEP, where and how should one start studying formal epistemology?
I don't understand what you mean by formal epistemology.
If you want to create new knowledge the knowledge you create often doesn't fit in to existing formalisms. So if formal epistemology involves describing the creation of knowledge in terms of formalism, then it's not going to be any use in most interesting cases.
As far as the use of logic in epistemology is concerned, a lot of the field is still enamoured with inductivism and the idea of justification despite the enormous unsolvable problems with such approaches and the existence of a viable alternative:
My main recommendation is to read the references given in the answers I cited above.