It is only my opinion, but I believe you are better off filing for an extension (if that becomes necessary).
With an extension, you can e-file your return whereas if you amend, you need to print and mail the return (i.e., amended returns cannot be e-filed).
You can (and probably should) estimate the total income and ensure that you do not incur a penalty for underpayment. The mere fact of having filed an extension (or amendment) does not abrogate the need to make timely payment of your tax liability.
See https://www.irs.gov/taxtopics/tc306
