How long for a local business to show in the map pack?

How long can you expect it to take for a local business to show in the map pack. (I dont just mean the three pack but the search results in maps in general) I have a local business, we have built up reviews and citations etc but are nowhere to be seen. The only place I have seen it is when searching the business name. I have read that it is harder to rank a service area business but thought it should at least be showing up by now...