Best tatics for single application using multiple databases?

So we want to set this:
One application <> multiple databases (one database per client).

I’ve tried MultiTenant hibernate implementation, but it seems I can’t add a new datasource in runtime (or I just don’t know).

The case: a lead signs up in our application. We have to create the whole database isolated and set the application to uses it in his connections.

Can I use multiple session factories? Is there a limit for them?
What is the best practice for this case?

Thank you for your time.