If you read online guide for VAT registrations from various sources, you can read that registration can take as little as a few weeks in some countries. This can be very deceiving, as in many cases offical documents such as certificates, certified identification documents, apostilles, etc, are required and can take weeks if not months to requests. For example, the IRS has a current turnaround time of just over 3 months to issue 6166 certificates.

So its best to plan ahead and start the process as early as possible.