Hi
I would start with dates & times in their own columns. You are over complicating things as well, with overtime between 11:30 PM - 7:30 AM and regular time between 7:30 - 11:30 PM you will need a bunch of IF's, AND's OR's etc. Probably why your not getting much response to your post!
Here's a link to working with Dates and Times
Bookmarks