Updating a bound component's value

I am doing the video tutorials here, specifically the first 2 on the page: Onboarding Part 4 - Data resources & REST - AppGyver

This is the tutorial where you have a local data object that holds reminders, and when you click on one of the reminders in the list, it takes you to a new page where you can type in an update to the item via an input box. But I want to change this to have the current value in the input box from the start.

I tried to use an event and set the newReminder value – bound to input box – from the singleReminder value to have the newReminder. I tried doing this when singleReminder is changed but this seems to happen over and over again, so this does not work. I tried to do it when the page is created/mounted but these events seem to be too early before singleReminder is set.

How do I do this?