Should i apply for H1B Extension

Hi Friends

I have my H1B till Sept 2018 and I140 Approved. Now I have below options with pros and cons , need your advise which one should I choose.

  1. File extension now On premium if for whatever reason it gets Rejected I can look for any other employee to file H1B based on my approved I140

2)File towards the end of the Visa that way I can stay in US for some additional day irrespective of the decision of H1B extension

Hope on any of the above scenarios there will be no impact on my GC processing.

*Please note I will complete my 6th Year in Sep 2018