I arrived in Quebec [x] number of years ago. Am I considered a newcomer or an established immigrant?

You be the judge! If, for example, your objectives are to practice French, expand your network of acquaintances and discover new places and activities, then you could participate as an arriving twin. If, on the other hand, you already feel well integrated, have a good command of French and feel capable of accompanying someone as they discover their living environment, then you could be a welcoming twin. All this can be discussed at the meeting with the community agent.