As per as your question, you want to apply the catalog rules for those products which has created in first month.
That means in this case you need to use product attribute
created_at and using this attribute,you need to apply the catalog rules.
Step1: create a new product attribute
my_attribute and make
Use for Promo Rule Conditions field should be
Export list of product skus which has been
created at the time of 1st using Magento
default export system (
csv with sku,my_attribute. put my_attribute
value 1. Then import this csv using
magento default import system .
my_attribute has been enable at promo, Now you can easy see the attribute to Catalog price rules condition attribute list and just put it value 1.
Now it will works