After choosing your name and talking to Prof. Oak, you will arrive at your house in New Bark Town. Head downstairs and greet your mother. Your mother will talk about four options - Bag, Your Name (the gym badges), Save and Options.
After you head out, a small Marill will bump into you, apparently looking for its owner. You will see Lyra (if you choose Ethan) or Ethan (if you choose Lyra) coming out of Professor Elm's home/lab and Marill happily run into her, and they'll go away.