This very early Allegro by Mozart, K.1b, is a simple and cheerful piece from his childhood compositions. It serves as an excellent introduction to classical form and style.
Focus on clean, precise articulation and a steady tempo.
Allegro in C major (K.1b) is rated Henle level 1 of 9 — beginner repertoire, roughly ABRSM grades 1–2. In the RCM system it corresponds to about level 2.
You should be comfortable at Henle level 1. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Allegro in C major (K.1b) lasts about 1 minute.
Allegro in C major (K.1b) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.