We don't know anything more about other wizards, or a council, until the very last chapter of 'The Hobbit', when, in Rivendell, on the return journey, Bilbo overhears conversation between Gandalf and Elrond and reports, "It appeared that Gandalf had been to a great council of the white wizards, masters of lore and good magic; and that they had at last driven the Necromancer from his dark hold in the south of Mirkwood."
So, it is a council of white wizards, but not yet 'The White Council'. (Which has morphed into something more than a council of wizards by TLOTR).
"A great council of white wizards", seems to imply that at this stage JRRT perhaps envisaged many more wizards than the 5 that eventually are mentioned (only 3 of which ever appear in TLOTR).