Only if you delete the previous version without copy pasting the save folder into day 11, if you transfer the folder from 10 to 11 then all will be fine.
If I remember correctly the code was 5911 (The girls birthdays.), sadly if you use it on day 3 you don't unlock anything except some cartoonish wallpaper about cats as you are not supposed to reach there yet. (You get another chance in the second week.)
