Hello guys...i need help with this problem...i'm creating a Bistro system...now i'm doing the Reservation part...i'm having some trouble here...its like this :

Start Time :

End time :

And there is a button, to show my table...the button is green in color at first(to show its available)...once i click it, a panel appears asking for those input...after that the button changes its color into red(not available)...once the end time is reached the button changes back to green...i used timer tool, but its hard since you can have reservation on different days....i would appreciate if u guys can supply me with ideas....