Min/Max with Times and Conditional Formatting

Good Morning,

I am seeking help create a populating schedule/gantt type chat for bud scheduling, the first function i need is for cell I3 to find the earliest time of arrival and then the headings subsequently to increase in half an hour increments, I cannot get this to work with the 24hr clock function.

The second job is to get the conditional formatting for each pattern (bus schedule) to colour itself within the correct time frames, again i cannot get around the 24 hour clock and setting the > and< to work correctly.

Any help will be much appreciated.

Regards.