Once you have settled-in, you will be required to visit the Office of Citizenship and Migration Affairs to apply for eID card (includes digital eSignature). During an in-person visit you will have to submit biometrics (digital photo and fingerprint scans) as well as fluorography (chest x-ray) results and health insurance policy with coverage of repatriation costs.
You can start working for your employer only once eID card has been issued to you.
Exception: this step does-not apply to holders of long-term D visa for work and unlike holders of temporary residence permit or EU Blue Card they can begin employment with their employer straight after moving to Latvia.