From the Department of Labor: Generally, the law requires plans to pay retirement benefits no later than the time a participant reaches normal retirement age. But, many plans, including 401(k) plans, provide for earlier payments under certain circumstances. For example, a plan's rules may provide that participants in a 401(k) plan would receive payment of his or her benefits after terminating employment. The plan's SPD or Summary Plan Description should set forth the plan’s rules for obtaining the distribution as well as the timing of distribution after termination of employment.
I suspect the precise answer to your question will be answered by obtaining a copy of the Summary Plan description, which the employer must provide to you under federal law (ERISA).
This is general information only and does not constitute legal advice, nor does this communication in any way establish an attorney-client relationship. Feel free to contact me for further information.