> When can I actually start with the burnination? When is it 'approved'?
This should be decided on a case-to-case basis. You should take into account the popularity of the tag, how long ago the Meta discussion was posted, the post score (preferably break this down into the number of upvotes and the number of downvotes, not just the resulting score) and comments or answers giving convincing reasons one way or the other, especially those by high-reputation users and moderators.
Popular tags should be given more time and/or a higher score before deciding to proceed with burnination.