I've never gotten any information from an amended return except a letter after it was completed, saying my return was adjusted and a refund was on the way (and the letter usually arrived after the check).
I don't know any way of forcing the IRS to bump your return to the front of the line. I think you just have to file as if it would be accepted, and then amend later, unfortunately.
Alternatively, if you have already paid your taxes, there is no actual monetary penalty for filing late, but you may lose other statutory benefits. So I would pretty much think you can wait until October 17 but then you need to file, using the best info available to you.
