How to get your expanded house without waiting a day
When you go to Nook's Homes and ask Tom Nook if you can expand your house, he'll tell you how much your loan will be, then he will tell you that your house expansion will be completed by the next day. After you do this, save and quit the game. Wait until the title name pops up and when it says press A (If you immediately press A, Isabelle will tell you that you didn't save and you'll lose the expansion deal). Select continue, then your file. When Isabelle asks you if you want to get started, select "I need help first..." then select change time. Change the date 1 day ahead of today and put what time it is right now. After that, begin playing, go back into your home after you exit. You'll see that your house expanded! Save and quit again. Do the same process but change the date back to todays date and set the time to the current time. Start the game, go back into the house and you'll see that nothing has changed! If you do not want to pay your loan, do not go to Nook's Homes, but no renovations will be made. Enjoy your expanded home!
Added by: Raxxyl Jun 28th 2013, ID#706