How can I create module like monthly regular customer received notification like, your monthly order is ready, get it. How can I do this for my customer.
You can use crones in Magento.
Something more about it :
In cron - Model class You have to write code sending email for your customers.
Oh important is how to set crons works like You want (eg once for motnh):
There is AOE Scheduler for manage crons for Magento 1