Counting Rows
 

I have a sheet in excel, where a user imputs data on one row together with time they were taken. I neet the excel to count the number of inputs every 8 hours and enter the number into another sheet.
I had been using VB to operate this. I wanted to convert the time into minutes and then use if to set the range and count the rows. but I dont know how to do this. I will appreciate any idea.
Cheers