zero padding (e.g 9:00 –> 09:00)

hello,
This is a great useful plug-in.

I’m trying to change the style of time slot, but I have no idea.
To make the time slot width the same as the others, I want to add “0” to the beginning of a single digit.

for example…
[9:00] –> [09:00]

the [09:00] button has same width [13:00] button.

and I want to add “0” the list that appears below when clicking some slots too.
Is it possible to set them?

(I would like to apologize for my poor English.)