As a follow-up to the morning's Hogwarts Express reveal, J.K. Rowling confirmed that Harry and Ginny Potter's firstborn, James Sirius Potter, was unsurprisingly Sorted into Gryffindor House.
Rowling admitted that September 1, 2015 was the first day of school at Hogwarts for James Potter.
Also of note is that Harry Potter's godson, Teddy Lupin (son of the late Remus Lupin and Nymphadora Tonks) was not only Sorted into Hufflepuff house like his mother, but was Head Boy the same year as James' first year.