Reverse chronological order is one option. But then you'd want to move the Add Comment field to the top, above the existing comments.
The other option is simply to automatically scroll to the bottom (most recent) comments when initially drawing the window. This way you could preserve the chronological order and the placement of the Add Comment field.
Thanks for the suggestions @Michael Lowry I've asked out DEV team to implement the auto-scroll option to prevent us from also having to move the Add Comments section.