No - don't amend your return.  The IRS and Treasury Department are developing a website for taxpayers who are expecting a check, where they can provide their bank account information in order to receive their Economic Impact Payment by direct deposit. According to this message on the IRS website the IRS will notify taxpayers when more details are available.

I filed on 4/1, and received a msg that the return was accepted. I have tried repeatedly to access the Get My Payment portal, without success at all. 

It is now 4/19. How do I know if the IRS has even going to give me a stimulus check, let alone add my direct deposit info.? This is very troubling.