Nook’s Cranny will be one of the first things you end up building on your island that isn’t your own tent. This useful shop will allow you to buy more interesting items than the meager wears that Timmy Nook can fit in his little tent.
Building Nook’s Cranny will be something you are asked to do quite early in the game when Timmy asks for your help building a new shop for the island. That is not its final form, however, and it can be upgraded to something even better.
To do this, you will need to spend money in the shop. A lot of money. Every Bell you spend gets you a little closer to upgrade the shop, as just like a real business, the more money it makes, the more Timmy can invest back into the shop.
At the moment, we don’t know exactly how much money you need to spend there, or if the upgrade occurring is in any way time-gated. As long as you are playing through the game, and spending Bells at Nook’s Cranny, it will eventually upgrade to Nookling’s automatically.
Just make sure you are visiting the shop every day, buying as much as you can from it, and earning plenty of Bells so you can keep the commerce flowing.
When it happens, an announcement will be made to let you know, you won’t need to do anything special to make it happen other than spend enough cash, and play the game for long enough.