Since many mailed returns are sitting in stacks near operations centers unopened, there is no way to know for sure the IRS received it until they open it and start processing it. The IRS has not indicated how long it will take them to work through the backlog. Amended returns take 16 weeks or more to process in normal times so you may have a long time to wait. Just continue to look for the status using the IRS tracking web site: https://www.irs.gov/filing/wheres-my-amended-return
