What is happening in this scene is when Quinn ran to go throw up in the forest. He ran out here to not make a mess back at the rest stop, and so he could be alone for a few seconds. This was probably around noon, and he got there by running
This scene is depicting the past, when Quinn went to a Halloween dance with Kneecap. It was most likely at night. They probably went because they just felt like going, although they most likely had to convince their parents to let them go.
The Final scene is when Quinn is talking to Kneecap and his mom. He got there after throwing up in the forest after he threw up, and after cleaning up after himself. He is there to talk to his mom and his brother, Ollie while he was at the rest stop. He is able to talk to them for only a short while before he had to get back to running