Now, It is poping up when the end time has passed.
I want it to pop when there is 3 hours left to reach the end time.
I mean it should throw a reminder so that the order should not cross end time.

Then my guess is that your code differs (logically) from mine. My
variable 'c' cycles through the end times. If c is past, then c -
Now() < 0 and the first if-condition fails.

Please be so kind to explain the logic of 0.125 which you have used in the
code.

0.125 = 1/8 3 hrs = 1/8 * 24 hrs

Hth,
Merjet