A plugin that lets you make Timeline JS timelines in WordPress based on post categories. This keeps things easy while keeping your data in WordPress rather than in a Google Sheet. You can get the plugin on GitHub.
You can combine it with Gravity Forms for the full SPLOT experience. This post gives you the function that allows you to backdate posts made in Gravity Forms. You can get that plugin here and the form, if you’d like to import it, is here.