Save time slots as dates?

I know this topic has been covered several times but I can’t seem to get my head around it. Essentially I am trying to achieve something similar to below where users are able to set their working hours by simply choosing a time from “start” and “end” dropdowns. The difficult part is then storing these times as dates rather than texts. Any suggestions?

Bumping up

Here’s a solution for you! (Albeit way late in the game)

If you’re in need of an intelligent timeslot creator or timezone aware calendar, this may be of interest!