There are several dates throughout the year that are notorious for wreaking havoc on businesses via DDoS attacks, data breaches and even malware or botnet assaults.
According to Radware, there are two types of dates that hackers target: ideological and business-relevant dates. Ideological dates refer to holidays and anniversaries that have a cultural, religious or secular tie to the adversary. High-risks times for the United States include September 11th, Memorial Day, Election Day and Independence Day. Business-relevant dates involve a period of time that companies are particularly vulnerable to attacks, such as Black Friday, Cyber Monday, or even regular business hours.
Additionally, hackers commonly use important dates and holidays to disrupt specific industries. For example, retail and credit card companies see a significant rise in cyber attacks between Thanksgiving and Christmas, whereas government websites may be targeted during Election or Independence Days.
via Timing is an influential risk-factor for cyber attacks.
Good but generic advice in the article. If you work for a multinational you'll need to keep in mind dates and events beyond the US - the football (soccer) World Cup, for example. User education is important but the returns diminish over time, especially if you cause fatigue in your users. Pen testing is good as well as a commitment in time and money to a security infrastructure life cycle management.