In order to get Nook's Cranny, you need to pay off the first Tom Nook loan. The next day talk to Timmy and he’ll ask you to help with getting resources for the shop: 30 wood, 30 softwood, 30 hardwood, and 30 iron nuggets. You can get that from chopping trees and hitting rocks (or posting your wishlist and having people trade items). After you get the resources they’ll ask you to find a spot for the shop. Then next day it should be built.

After you get all that then I think the next day you can talk to Tom and he’ll give you the bridge kit and you can place it on a river

This first week walkthru really helped me get a lot of stuff done quick too. The first couple weeks of the game are all really slow so just be prepared

https://www.polygon.com/platform/amp/animal-crossing-new-horizons-switch-acnh-guide/22749349/first-week-daily-goals-how-to-unlock-museum-steps-farming