AddTimestamps
This is a tutorial how to add timestamps in batch to a lot of pictures.
Install irfanview from www.irfanview.com
Start the application and go to "File"/"Batch Conversion/Rename..."
The screen is a bit daunting, but if you pay attention to the buttons/fields having a red circle in the following screenshot it should work out.
First, check "Use advanced options for bulk resize,...) and click the "Advanced" button.
The next rest of this tutorial will explain what to fill out there... and at the end you can come back to this screenshot to take steps 2 to 4 in the screenshot.
In the advances options, enable "Add overlay text", and click the "Settings" button
In the settings screen, you can choose which text will be "printed" inside the pictures. The values choosen in the following screenshot should give a decent result. You can tweak it afterwards to your own liking...
Go back to step 1, and proceed with the other parts of the screenshot that are "circled".