Once you have a decent amount of Peat, be careful where and how you place it! If you’re in a Swampland biome, you can place it anywhere you want without consequences. However, in any other biome it’ll soon dry out and turn into Dirt unless you keep it moist.
Luckily, Peat obeys the same rules as Farmland, meaning that any Peat blocks within 4 blocks of water stay irrigated regardless of the biome they are in. Unlike Farmland however, Peat blocks won’t be damaged if you jump on them.