You could create a text layer and type in date and time info for photos. I generally see this option as a feature of the camera. Are you taking photos using the tablet itself? What tablet are you using? If you are not taking them with the camera on a tablet you might check settings on the camera itself and consider transferring them to the tablet via the Creative Cloud Files website, note that camera images will most likely need to be resized to work within PS Touch dimensions.
I have an iPad 2 Andes using the tablet to take photos.
As the iPad doesnt have facility to print date and time on like a conventional camera, I have been looking for an app that provides this.
For evidential purposes alone this is a must and so far this is the only thing the iPad doesn't offer me for my job
I think this might be too specialized a feature to be something that every Photoshop Touch user would need/want. I went to the app store and just did a search for "timestamp" (no qoutes with the actual search). I did find some apps that read the metadata and can add timestamp info to photos. You might be able to timestamp your photos first with some other app then import the images into PS Touch.
Some of the apps I saw were
- StampPhoto - added timestamp and geotagging location info (included a little map of the location on the photo itself)
- phoTime - has a camera button in the app that adds the timestamp at the bottom as photos are taken
- Timestamp It! - New and existing photo support, change text color, custom date and time entry support
You might investigate these further, all were in the $1 app price range
Hope that helps,