So I was watching Boss Mabel and I kinda noticed the year on the book cover

is a year after Stan’s twin brother presumably got sucked into another dimension leaving Stan alone and desperate to save his brobro (with nothing but a bunch of notes and a broken multidimensional machine). Since then, he’s probably been doing everything possible to try to make ends meet and that’s when he bought the book hoping to start some kind of business. Like, he probably didn’t know shit about starting a business and he learned everything from that book (including having to wear shoulder pads lol).