If you have a refund coming from the Amended which you would have, then yoou actually have up to 3 years from the due date to file an Amended return.
However I would do it in about 2 to 3 weeks (so IRS can process the first return filed) and file it and be done with it.
Or do it now and mail in about 3 weeks.
https://ttlc.intuit.com/replies/3288565
