Online retailers should begin their back-to-school promotions and pay-per-click campaigns by August 5, or risk being held back, according to MarketingExperiments.com's online merchandising calendar guide, DM News writes.

The merchandising calendar outlines when promotions should begin to help retailers maximize seasonal sales, year-round. It also offers 11 key points to help merchants apply the calendar to their marketing efforts. The calendar shows that beginning campaigns by the August deadline is important if retailers want to optimize natural buying trends online.