You will get a letter from the IRS in about 30 days explaining the changes.

When you amend your return, the TurboTax software should already have the changes made.  That is because the program has been changed to show the first $10,200 of unemployment being excluded.

Those changes should pull through to the state.  Your state amend should automatically show the amount that the state will refund to you. 

You should be able to just amend and only submit the state amend to be processed.  But double check those figures to be sure that the unemployment has been excluded from the state amend.