If I were you, I'd consider writing a little Python script to do this, pulling in
pyexiv2. It's extremely easy to use:
>>> metadata = pyexiv2.ImageMetadata('test.jpg')
datetime.datetime(2004, 7, 13, 21, 23, 44)
Note: Different cameras use different fields for dates. Check first to see what keys are available.
It should support raw images. I know it does for the NEF raw files my Nikon creates.
If it doesn't, do you have JPEG versions too with similar names (ie different extensions)? Even if it can parse your RAW files, it might be worth ticking through the JPEGs for its EXIF data because it'll likely be a bit faster.
Tip: You can use the Python shell instead of having to write a "proper" Python script. This is good for testing things out but if you want something you can use over and over again, you probably want to write a script.