Already filed for 2016, just notified I will receive a K-1 Form. Do I need to request an extension or just amend return when form comes?

I already filed my 2016 return and received my refund.  However, was just informed that I will be receiving a 1099 and a K-1 Form (of $61.31) for stock I have in a Company that switched over in 2016 to giving gain disbursements (no clue this happened until recently).  Can I use Turbo Tax to amend my return when I get the forms (Should get them in the next 1-2 months they said).  Is there a time limit to file once I receive the forms? Do I need to file for an extension or not since I already filed for 2016?   I am so confused…