If you are already certified in West Virginia and waiting on reciprocity in another state, still working in West Virginia until you are accepted on the other registry shouldn't be a problem.
If you are certified in another state and waiting for reciprocity to WV, your employment may be up to the facility where you work, but West Virginia's transfer process does not take long once you apply. An immediate turnaround is not guaranteed, but it is generally not a very long process either. A little secret: OHFLAC tells applicants the process can take up to thirty days for good measure, but it generally only takes a few business days at most. They cannot always give a more specific answer because, as irony goes, issues beyond their control will hinder the process, and then they deal with more upset customers than usual because it wasn't done "in time".
Also consider that while OHFLAC receives applications at any time, applications are generally reviewed during typical business hours and workdays (excluding holidays). So, for example, if the NAP receives an application on Friday night, chances of receiving an approval or response before Monday (or the next workday) are slim to none.
Also, your submission to WV is just that: a submission. It does not automatically grant or guarantee approval. Your application is reviewed during business hours and you will be contacted via email regarding your status, communicating either that you are approved or how you can meet our criteria to be approved. (Check your spam or junk folders in case the correspondence got redirected) However possible, you might actually want to consider these facts when planning for work opportunities that depend on your approval.