In Breaking Bad, Saul looked like a man in his late 40s. I want to know - at the beginning of Better Call Saul, how old is James McGill?
According to the Breaking Bad Wiki (I have no idea where they get this stuff...), Saul is in his late 40's during that series. Since Better Call Saul is supposed to take place 6 years prior to Breaking Bad, you can assume he's supposed to be in his early-to-mid 40's at the beginning of BCS.
41 years old
In Better Call Saul Season 5 Episode 7, "JMM", in the scene where Jimmy and Kim were applying for their marriage license, Jimmy's date of birth on his driver's license was revealed — November 12, 1960.
Season 1 was set in May-July 2002, so Jimmy was 41 at the beginning of Better Call Saul.