I hear this a lot in my personal life; 'it's the little things.' Yes, ok, I get it. But little things also matter in a big way in business.
At the transition into any new year we are bogged down with budget planning, year-end reconciliation, reporting, contracting new vendors and a myriad of other things. But these are all big things and, while important, should not be on the only thing on your new year's to-do list.
Where to use date stamp in your materials (if you really want a date)
There are only two places that I see necessary to have a date indicated in your materials.
1. Your website in the footer
2. PowerPoint template footer
Where NOT to use a date stamp in your materials
I see whitepapers, case studies, datasheets and a slew of other content with publish dates and i'm not a fan. The number one reason I really don't like this practice is because you a likely have content that is evergreen, meaning you can use it now even though you wrote it 2 years ago. However, that paper you published in 2017 and is stamped as such in the copyright, is disregarded as 'old' before they even read the first sentence.
Don't lose the copyright, just don't indicate a year
Another way to approach this across all your media and content is to NEVER indicate a year. Mark the copyright as your property and that's that.
TIP: Add a to-do in your calendar for Dec 31 every year to update the date to the new year on any materials where it is referenced.