The amending option is supposed to open on February 19. In the meantime, do not make any changes in your return. When you begin the amending process, it has to start off as originally filed.
If you were due a Federal refund, you should wait until your original return has been fully processed by the IRS, and you have received the refund.
If you amend the Federal return, you may need to amend the state return, too (if applicable.)