InfoWindow Customization

I have a ACF for date that only stores the date in the 20190318 format to the database. I need to include the date in the infowindow in a different format. I’ve tried to use javascript in the infowindow are but that doesnt seem to work. The other option would be to have a javascript hook so I know when the map is done and I can then target a data-src value to reformat and then change in the infowindow via jquery.

Thoughts?