"Albus Severus [...] you were named for two headmasters of Hogwarts. One of them was a Slytherin and he was probably the bravest man I ever knew."
-- Harry Potter
Harry and Ginny bring their three children to Platform 9 3/4 and the Hogwarts Express. They meet up with Ron and Hermione and their two children. Harry and Ginny’s second son, Albus Severus Potter, along with Hermione and Ron’s oldest child, Rose Weasley, and Draco’s son Scorpius Malfoy all are beginning their first year at Hogwarts. Just before the train leaves, Albus confesses his fear of being sorted into Slytherin to his father. Harry reminds him that one of his namesakes was a Slytherin and Harry tells him that Snape was the bravest man Harry ever knew. He reassures him, saying that the Sorting Hat will take his choice into account. They part and Harry watches as the Hogwarts Express departs.
Calendar and Dates
The name of the section - nineteen years later - tells us that this is 2017, the day is named in the first paragraph (BH) and September 1, 2017 is a Friday.
Interesting facts and notes
Two large cages...the owls inside them hooted indignantly
So James and Albus each have their own owls instead of having to share.
'Two years,' sniffed Lily. 'I want to go now!'
So Lily Potter is nine years old.
'We wrote to James three times a week last year,' said Ginny.
James is at least in his second year (and probably not much older than that, I would say).
Harry thought he heard Percy discoursing loudly on broomstick regulations, and was quite glad of the excuse not to stop and say hello...
Since Percy isn't seeking out Harry or Ron, he isn't there just to see their children off. Consequently, it seems likely that he is there to see off his own child or children, but we don't know for sure since none of the rest of the family actually see him during this scene.
Rose, who was already wearing her brand new Hogwarts robes
And since this is Rose's first trip to Hogwarts, she is roughly the same age as her cousin Albus.
'Parked all right, then?'
So Harry drives a car instead of always travelling magically.
Since nineteen years have elapsed since the Battle of Hogwarts, Teddy is now just past nineteen. Since his birthday is sometime in April or thereabout, he would have begun at Hogwarts at the age of eleven and left at eighteen, so he's been out of school for over a year.
he said he'd come to see her off!
So Victoire is still young enough to be in school, but old enough to be involved with Teddy without shocking anyone but James. :) She would be at most seventeen, or she'd already be out of school.
Don't forget Hagrid's invited you to tea next Friday.
Just as he invited Harry to Friday tea at the end of his first week (PS8).
Don't duel with anyone 'til you've learned how.
Harry could have done with this advice during his first year (PS9).
All was well.
Rowling talked about the last sentence of the book with Meredith Vieira on the Today Show (Today2):
MV: The end of the book... I had read that the last word was supposed to be "scar"...
Jo: And it was, for a long, long time. For a long time, the last line was something like "Only those whom he loved could see the lightning scar." And that was a reference to the fact that Harry was kind of flanked by his loved ones...
MV: To "All was well."
Jo: All was well.
MV: And you know when you came up with that line, that was it.
Jo: It just felt... I felt a kind of [sighs] and that felt right.
Exceptional character moments
Albus Severus Potter, worried sick he might be Sorted into Slytherin.
James Potter, yanking Albus' chain at every opportunity, and who is too cool to give his mother's love to Professor Longbottom.
"Hermione didn't believe I could pass a Muggle driving test, did you? She thought I'd have to Confund the examiner... As a matter of fact, I did Confund him."
"'If you're not in Gryffindor, we'll disinherit you,' said Ron, 'but no pressure.'"
"'So that's little Scorpius. Make sure you beat him in every test, Rosie. Thank God you inherited your mother's brains.'"
"'No,' said Harry firmly, 'you and Al will share a room only when I want the house demolished."
"I thought they were invisible? You said they were invisible!"
"What if I'm in Slytherin?"
"It's me. I'm extremely famous."
"The scar had not pained Harry for nineteen years. All was well."