For needs that only concern you, you need the time and date of your spy camera to be accurate. Regardless of the model or type of camera (spy watch, spy glasses, etc.), the adjustment procedure remains pretty much the same. 

Check the notice and contact the manufacturer

When you buy an electronic device, the reflex to have in case of a problem is to refer to the notice. As a general rule, this document explains at length the various steps for good use of your device, from start-up to innocuous gestures such as installing the SD card (if planned). And this also applies to spy cameras.  In case the advice of the notice is incomprehensible to you, you always have the option to contact the manufacturer of your spy camera. If this is not possible, you can also contact your seller when they have customer service.

Change the date and time yourself

If you want to change the date and time yourself, the procedure is very simple. On your computer, plug in your spy camera. "Removable disc (H)" should appear. Now, with the "notepad" application of the same computer, create a file called "time.txt." On the first line, note the date and time of the time in the format "year.month.day hour.minutes.seconds" followed by the letter "Y" to display the time under the video, or "N" otherwise. To set the date for Christmas 2019 at 6:30 a.m., you will get "2019.12.25 06.30.00 Y". Once registered, send the file to the "H) disk, just like the DCIM documents. Depending on your device, the file may need to be renamed "userset.txt," "userconfig.txt" or "settime.txt."