Image SEO

I recently rebuilt a website from scratch for an artist. Due to the nature of the site, it is really important that the images get picked up by SE's. It's been 3 weeks and they have not (maybe I'm impatient).

The image file names and alt tags are respective to the title of the painting or print. The thing is, the titles of the art works are really random and don't contain any "keywords." I'm wondering if the the file names and or alt tags should also include the name of the artist. Also, does the directory name that the images are contained in matter? Oh, and how long should I expect to wait for the images to get picked up by the SE's?

-Thanks

how do the image file names look like?
and how many images/page do you have?

like "title.jpg"

right now, about 100 images, each with its own dynamically generated page, all with static links from a thumbnail page, and the number of images is growing.

see for yourself if it helps: www.brucethorn.com/paintings