Yes, you can amend as soon as the federal amended tax return form 1040-X is available for filing in TurboTax. The IRS requests that if you are amending to get an additional refund, you wait until the original is received. But since you will owe a balance, you can go ahead and amend right away. Use this tool to check availability of forms, including 1040X: Tax form availability
Here is some more information on filing amendments: How to File an Amended Tax Return with the IRS