By default it takes around 5 days for a palm tree to produce its product.
You can change the product and the days in the config using Generic Mod Config Menu, or editing the config.json file.
The product can be a vanilla index or vanilla name; DGA and JA names should work as well.
Technical
Requires SMAPI, uses Harmony.
Compatible with Mod Updater for automatic updates.
Code is at https://github.com/aedenthorn/StardewValleyMods.
If you want to complain or ask for help or help me test my mods, you can visit my Discord server.
A list of all my mods for Stardew Valley is available at https://www.nexusmods.com/stardewvalley/articles/895.