Moment.js was one of our biggest dependencies, and the transition to Day.js was easy. I'm certainly glad we didn't hold off. I'm sure we'll switch to Temporal eventually, but it's misguided to suggest everyone should wait a year or more to improve their sites just to save a little effort in the interim.
One has also got to hope that Temporal offers all the features a well built daytime library does offer. What good is it if Temporal is lacking that one feature you need, so that you end up including another library as well.
By then you can assume that the other library will be a lightweight wrapper around Temporal.