Go to https://passportstatus.state.gov/ and enter your details (only need your last name, DoB, and last 4 of social). Your locator number will show up in the results.
Got interview scheduled today (notice dated 2/17/22) for 4/1/22 in Portland. Submitted application on 6/19/21; last update was biometrics reused, also on 6/19/21.