Topic: H1B Expiring

Hello Folks Thanks a lot for the help. My current situation is : I have a approved I140 with a priority date of Sep , 2011 . I have a current valid H1B , which is going to expire in the next 3 months. Question is : Do I absolutely need to keep my H1B visa valid and in status for the next step of GC when the I140 priority date comes valid ? As per the great GC calculator on this site , that is going to happen sometime in 2020 . Please let me know your thoughts/views on this. Regards Saroj