Question about tax amendment. I just recently filed my taxes through HR Block.

I pulled a real dumb move and forgot that I collected unemployment and just received my 1099G form. I understand that I have to wait for my return to be accepted by the IRS before filing an amendment. 

These are the questions I have:

Will I still get my return as normal and then the ammendment will be a separate return or will the current return I have in be "canceled" until the amendment processes and then sent out at a later date? 

How long do I have to file an amendment once the IRS has accepted my return?

Is it possible to just not file an amendment and file the 1099G form with my taxes next year?