It is recommended to pay any balance due by Tuesday, April 17th, 2018, to avoid any penalties and interest. However, if you are unable to make the payment, you may request an installment agreement.
It usually takes 3 weeks for the amendment to show up in the IRS system and can take up to 16 weeks to be fully processed.
After mailing in your Form 1040X and waiting a couple of weeks you can apply for a payment plan online at the IRS Payment Plans and Installment Agreements web page.