reading a text file at certain timeouts

i have a text  file lets say in this format

abc abs ajfhg agjfh
fhs ghg jhgjs fjhg
dj djk djghd dkfdf
....
....
......

i want to read the first line at certain time for eg : at 10clk
and the next time when i am reading the text file for eg a timeout of
10 min (@[EMAIL PROTECTED]
 10:10) i want to read only the second line skipping the
first line
and at 10:20 (again after timeout of 10 min) i wanna read only the 3rd
line skipping 1st and 2nd lines
and so on...

this 10 min time is not fixed..it varies for line to line....i wrote
this time for convenience...

i tried with a counter such that when i read the first line i am
incrementing the counter and comparing when i am read the next
time...somehow i am missing something, i am not getting the proper
result...

thanks for any help..