When should a body corporate be formed?

I own a villa in a group of nine built several years ago. Six have been sold while the remaining three are still the property of the builder, (although up for sale). While I’m happy not paying strata levies at the moment I was under the impression that once the majority of villas were sold then a body corporate should be formed. Also, where do I stand if I wish to build a verandah roof? Do I need approval from anyone other than the council? Would it be easier to do it before a body corporate is formed?

Chris, Menai NSW