In a NY Times article today, they answered a lot of questions people have regarding the stimulus package. Here is an excerpt that is pertinent to your question:
Will I have to apply to receive a payment?
No. If the Internal Revenue Service already has your bank account information from your 2019 or 2018 returns, it will transfer the money to you via direct deposit based on the recent income-tax figures it already has.
What if my direct deposit information has changed or I want to add it for the first time?
On March 30, the I.R.S. said on its website that it would build a portal where people can update their information “in the coming weeks.”
When will the payment arrive?
Treasury Secretary Steven Mnuchin has said he expected most people to get their payments by April 17. Presumably those people using the new portal would not get money until a few weeks after they are first able to provide their information. The I.R.S. has not said when those receiving paper checks would get them.
The full article covers a lot more. I would post the link, but can't here. Maybe try googling NT Times and the article title:
F.A.Q. on Stimulus Checks, Unemployment and the Coronavirus Plan
