Is there a standard as far as how soon after hiring someone they have to register with the NMLS?

Before they hit six loans as long as they've never been registered before:

De Minimis Exception — Section 1007.101(c)(2)
The SAFE Act regulation provides an exception to the MLO registration requirements for any employee of a covered financial institution who has never been registered or licensed through the Registry as an MLO if during the past 12 months the employee acted as an MLO for five or fewer residential mortgage loans.
When an institution relies on the de minimis exception in lieu of registration, the MLO employee must register prior to originating the sixth residential mortgage loan within 12 months. Covered financial institutions are prohibited from engaging in any acts or practices to evade the registration requirement.

source: https://files.consumerfinance.gov/f/201203_cfpb_update_SAFE_Act_Exam_Procedures.pdf

Thank you mtngrrl!