You can do a lot with five birds, especially when you have plenty of pet stock to use as foster pairs.
I would suggest holding off on buying more birds until you have been a member of a club for a few months at least. It takes a while to work out who is breeding the sort of birds that you would like to breed. For example, I know that for "Variety A" there is just one breeder I would go to for stock.
Go to shows, visit other club members set-ups and ask questions. Your aim of starting with 10 birds is a good one, but you need to do your homework first.
Good luck