I used to work in the Melbourne childcare scene and know pretty much every centre - have been to most and worked in about half as relief staff. Which part of the CBD are you looking for - where do you work, and where do you live? There are a couple that are fairly well tucked away and you might not know of them. Also, how soon do you need it? The best places won't have spots for over a year, so that's something to consider too.