No problem. "Night" refers to any time after school. After you leave school at the end of the day, you're into that period, and when you go to bed, it resets to morning. You then have to go to school again, after which the night part resumes.
The easiest way to get money is to clean for Emily. You'll meet her by progressing Abbie's relationship quest to the point where you need money. Karen will send you to Emily's to clean, and once you've seen that scene, you can return there once per day to get 20 credits. You can also sell items at the shop next to the washer woman in town, but that requires getting the items first, the maid work is a much faster and more reliable method. Finally, if you've completed chapter 3, you can win money by wrestling at the Pussy Pit in the red light district.