when you moved into a new neighbourhood you didn't have to wait long before someone called round to welcome you, and introduce themselves. Nowadays things may be slightly different, particularly in a big city.
People tend to hang back a little, and respect your right to privacy. Not everyone who moves to a new area wants to make friends with the neighbours, at least not until they've had a chance to settle a little and take stock. I think it's probably best to engineer a meeting outside the house, perhaps when you see the new neighbours putting out the rubbish for instance, and introduce yourself that way, rather than turning up on the doorstep.