Showing fields only if applicable

Showing fields only if applicable

I have set up some fields on my CRM. 
As an example they are:
Address & Date moved in. 

What I want to happen is if that address is less than say 3 years, for it to then pop up with Previous address and date moved in to that address.

I have the fields but I am struggling with how to condition them based on a time frame. Can anyone help?