In one of your comments (to gnasher729's answer), you mention that this is a startup. For me that changes the whole question.
Since this is a startup, it may simply be that they don't even know exactly what they are doing. Managing this type of process and all of the ensuing paperwork is typically something handled by a fully staffed HR department with all of the necessary expertise. Since you mentioned that this is a startup of around 10 people, I doubt they have much of an HR staff at this time.
If I got this kind of response from a corporation with thousands of employees, I'd be shocked that the HR department doesn't have better idea how to handle this and likely a fully documented process for the situation. However for a startup without that expertise, they are probably figuring it out as they go. Also, as a startup they are likely to have lots of other hot issues to worry about and if they are waiting on your paperwork to come in, this is not on their priority radar yet, and quite possibly won't be until that paperwork comes in.
The silver lining may be that as a startup they may also be more flexible in giving you time to relocate after the decisions are made, since they are used to adjusting to things on the fly.