Yes u can use blind references.
In early game u have very large stack and much big blinds, usually over 50 BB's.
Mid game or phase is when you are approaching the bubble, and than it ends. U usually have under 50 BB's.
Late game is when blinds further increase and your stack decreases. Usually tournament average is like 20 BB's.
I'm new here so I'm not sure if you have articles on CardsChat,
but you can seach on google "Early and Middle Phase" and also "The Late Phase" for detailed explenation.