When can I file a change of status from F1 to Investor visa? If yes, when can I change my visa status to investor visa?

You can apply for a change of status from an F-1 visa to an investor visa (such as an E-1/E-2 visa) if you meet the eligibility requirements for the investor visa. 

It is advisable to file for a change of status before your F-1 status expires. If your F-1 status expires, you may be considered out of status, which can complicate your application and may require you to leave the U.S. to apply for a new visa.