A/N: So, I know JKR said that Teddy was raised by his Grandmother, so I know this doesn't really go with the canon, but I just thought it was a lot easier to have Teddy live with Harry's family. Also, the owl is named Avis because it means "refuge in war or struggle" which is also the meaning of Hedwig.
The summer after Teddy turned 11, he remembered constantly reminding all the younger kids that he was going to be going to Hogwarts. Teddy thought it was only fair, because he was born first (and overshadowed first) and therefore should also get to go to Hogwarts first. He always remembered that summer, years later, of trips to Diagon Alley with Harry and Ginny, and his aunts and uncles coming home from work early to treat him at the new Florean Fortescue's and get him mugs of butterbeer.
The day he got his first Hogwarts letter, he kept glancing at that wonderful list of all the spellbooks and and supplies he would need. Harry and Ginny brought him to the wand shop, where he swished them around until he found one that was warm and tingly and didn't emit loud bangs and sparks, and he also got his own set of plain black robes. He asked Ginny to show him what was next on the list, and when he saw that he could get a cat, owl, rat, or toad, he almost burst with excitement and delight. They went to the Magical Menagerie, where Teddy inspected the animals with vague interest.
"Do you want a cat?" asked Ginny, scratching the fur on a gray kitten.
Teddy shook his head no.
"A toad?" asked Harry, holding a color-changing one in his hand.
"No," Teddy said, shaking his head again.
Ginny suggested that they go to Eeylops' Owl Emporium, so they left, the bells on the door jingling as they stepped out.
Teddy finally decided on a lovely snowy owl, and when he looked up he was a little perplexed at the tears in the corners of Harry's eyes.
When they got home, Teddy packed all his things in his brand new wooden trunk at the end of his bed, while his siblings looked on jealously. He set his owl's cage on his desk, and decided to name her Avis. He made Aunt Audrey hang red and gold curtains around his bed. On Wednesdays and Saturdays, when he went to visit his Granny Andromeda, he made her tell him stories about when his mother went to Hogwarts. Ginny decided he was old enough to use a quill instead of a pen or pencil, so he took one out and got a ruler and carefully drew a chart. Then he looked at Ginny's big calendar in the kitchen, and he copied down all the numbers until September 1st. He hung it up on his bedroom wall, and one day as he was crossing off a square, he turned around and saw Harry with that same watery smile. He made Aunt Hermione practice all the spells in the books with him, and had her read Hogwarts, A History: Revised out loud, though half the time he was actually imagining new friends and all his classes instead of listening to her. When Victoire came up to him and begged him to teach her new spells, he shook his head importantly and told her that she was too young, and besides, spells were for people with wands. Then he picked up a handsome new quill and wrote a pretend essay, making Aunt Hermione check all the mistakes.
Uncle Ron told him about the food at Hogwarts, and Uncle George sketched out a map of Hogwarts and told him where all the secret passageways were. He pulled Teddy aside and described to him a map that showed where everyone was, and all the rooms. "However," he said, "you need to know how to use it, or else it will just be a blank piece of parchment." Then he taught Teddy 'I solemnly swear that I'm up to no good' and 'Mischief Managed'. When Teddy asked where it was, Uncle George whispered in his ear that Harry had it. That was when Teddy noticed an ear lying on the ground, with a flesh colored string bending out of sight. When he pointed it out the Uncle George, they heard Harry laughing as he walked around the corner with a suspiciously innocent look on his face. He told Teddy to just use the map his uncle had given him, and the two adults walked off, both laughing now, as Teddy ran up to his bedroom to study his uncle's drawing.
In the last week, Teddy suddenly remembered that Harry had joined the Quidditch team in his first year, so he frantically made Aunt Angelina come over after dinner to practice catching the snitch with him. Harry came out one day, looking amused, and asked Teddy why he was practicing so much Quidditch, to which Teddy replied, "nothing." Later, as Ginny put him to bed, she casually reminded him that first years weren't allowed to join the Quidditch team, and he nodded with an, "I know."
The day before he left, he wrote letters to all his aunts and uncles and cousins. 'I'm practicing,' he wrote. The only part Teddy disliked about it was having to write what he imagined Hogwarts to be like, instead of what it was actually like. Mostly he wrote down the information all his relatives had given him. He spent the afternoon tying each letter to Avis' leg, then waiting for the owl to return, only to set off with a new letter. They All wrote back, his aunts and uncles reminding him that he didn't have to send each family member's letter separately. Then, coincidentally, Ginny came in later that day and told him, "no more letters." Teddy explained that he still wanted to write one to Hogwarts to tell them that he would be a wonderful student and to thank them for his letter. But Ginny said no, while Harrytried not to laugh, and Teddy cursed his aunts and uncles in his mind for telling on him. (He had heard a lot of swears over the years-he knew what words were forbidden from when Aunt Hermione shushed one of his uncle's after they said a weird sounding word.)
Ginny came in at 10:00 that night to find Teddy repacking everything. She made him go to bed, and the next morning he was up at 6:00, bouncing on Harry and Ginny's bed to wake them up. Needless to say, they were both very cranky and told him to go back to bed until they woke him up again.
At 10:30 all his extended family had arrived at King's Cross to see him off, and they hugged him, shouting off last minute reminders, the other kids asking him to write and Victoire sobbing as she clutched her mothers leg.
Teddy boarded the train, and when the Hogwarts Express pulled out of Platform 9 3/4 with a lurch and a puff of steam, Teddy couldn't be more excited.