Frequently on new site I see users ask questions from the Area51 proposal. That could be viewed as acceptably populating a new site with content or rep-farming.
Is asking questions from the Area51 proposal encouraged or discouraged?
If the community has taken the time to say "we think these questions are perfect for our site", it would be silly to not ask them on the actual site. Ideally it probably makes sense for the person who actually proposed the question on Area51 to ask it on the site, but if they don't another person might as well so the question appears on the site and gets answers