Hi - you have a few choices.
(1) file an "Extension" form now, or
(2) file now and amend later.
Last year I got form K-1 late and discovered for many companies the form is Online. Internet search for "Tax Package Support for (the company name)". Create an account. Your name on the account is the same as it appears in your broker account.
Example: for Enterprise Product Partners search: www.taxpackagesupport.com/enterprise
