The back-to-school season is already in full swing. It’s the second biggest spending event of the year—second only to the winter holidays. And retailers are advertising big sales that will continue for the next two months. More parents are starting their back-to-school shopping earlier. Almost a third begin a month or two before the first school day, and nearly 50% start three to four weeks in advance, according to the National Retail Federation. And many parents are spreadin