If your camera creates files with unhelpful names instead of date/time within the filename (e.g. "_A123456.JPG") , as long as there is Exif data within the image files, you can use
exiftool -fileOrder DateTimeOriginal -recurse -extension jpg -extension jpeg -ignoreMinorErrors '-FileName<${CreateDate}_%f.jpg' -d IMG_%Y-%m-%d_%H-%M-%S_%%.3nc ./
to rename them.
