Requested Start or WAIT which approach is Suitable?

Hi Good Day,

i have a requirment where i have 2 dates

1. Start Date and End Date.

ex : Startdate = 02.09.2013 and Enddate = 03.10.2013

if 02.09.2013 - 03.10.2013 = 30days then i need to send a MAIL as a  first remainder to Manager.

send a second remainder when it is 7 days to end date.

can anyone please explain to me as to whcih approach is suitable?

thank you,

J.