By e-filing your return and choosing direct deposit, you've chosen the fastest way to get your refund.
The IRS issued more than 9 out of 10 refunds in less than 21 days last year and expects the same results this year. This is 21 calendar days after the e-file has been accepted (received), not 21 days from the e-filing date. (For mailed returns, allow 5-6 weeks from the postmark date.)
Please see below for more details.
https://ttlc.intuit.com/questions/1899304-what-s-the-earliest-i-can-get-my-tax-refund