In Chapter 10, the chapter begins the morning after Quidditch practice. Knowing [[2 September]] is a Monday, the Thursday of the second week would be the [[12 September|12th]]. The morning after would be the [[13 September|13th]]. Then, it says "Just such a thing arrived in the post about a week later…". If we take it exactly a week later, we get [[20 September]]. However, from a few chapters back, we know that from Hagrid's note, [[Trio|they]] have Friday afternoons off. Then why would Harry wait until after dinner to unwrap it if it arrived at breakfast? It is possible this is on J. K. Rowling's part, but it may imply that the [[Nimbus 2000]] arrived either the day before or the Monday after.
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