Google tag manager can be use to track widget events.
Setup a widget on your page
Make sure the dataLayer exists in the parent window.
Note: This only works when you are using the widget setup script or the widget component. iFramed widgets are not supported.
When configured the widget should send the following events to the dataLayer
When the date picker is opened for the first time
When time picker is opened for the first time
When you are on the checkout overview page
When you are on the checkout notes page
When you are on the checkout details page
When you are on the checkout confirmation page
When a reservation is made