Per the IRS:
You can check the status of an amended return around 3 weeks after you submit it. You should generally allow 8 to 12 weeks for your Form 1040-X to be processed. However, in some cases, processing could take up to 16 weeks. You can visit our processing status dashboard for more information on our timeframes.
IRS - Where's My Amended Return?
IRS Amended Return Status
When you print a copy of your tax return(s), there is a page titled "ELECTRONIC POSTMARK - CERTIFICATION OF ELECTRONIC FILING" which will show when you filed your return(s).
You should also receive an "Acceptance" notification from the IRS when you log back into your account if you e-filed your amended return(s).