When did Harry Potter become friends with Ron Weasley and Hermione Granger?

Answer 1

Harry Potter and Ron Weasley became friends on the Hogwarts Express on their first day of term, the 1st September 1991. They were sorted into the same house and shared a dormitory. Except for a few arguments, they remained best friends throughout their lives.

The two became friends with Hermione Granger after they saved her from a mountain troll and Hermione lied to keep them out of trouble.

Answer 2

Harry Potter became friends with Ron Weasley, technically before Harry became friends with Hermione. Harry became friends with Ron on the Hogwarts Express, and Harry and Ron finally became best friends with Hermione after they fought the troll together in Harry Potter and the Sorcerer's Stone.

Answer 3

Hermione Granger became friends with Harry Potter and Ron Weasley after they saved her from a troll. The troll was let into Hogwarts on the 31st October 1991.