The technical and timing issues aside (this isn't even a site, yet) — generally speaking, you don't want to start a new site with questions imported from elsewhere. If there is a good questions on the Deep Web for this site, you should simply re-ask it.
Importing a question from elsewhere means the question and answers wont likely have an owner without an account. The tags wont likely match. The content would be anonymous, so any notifications from users asking for followup or clarification go nowhere. The voting is largely meaningless; any reputation that should go to new community members desperately trying to establish leadership is lost. Folks aren't nearly as likely to post new answers to a thread that was completed elsewhere. The post may not even follow the standards trying to be established by the new community.
Essentially, you are loading up a site with a lot of typing and text without any of the experience, responsibility, or engagement that goes with it. It's a site with a lot of bulk, but no substance. It's just a bad idea.
That's why we don't do it.