When I photograph stars for either a star trails photo or a time lapse, I usually shoot with my Rokinon 14mm at f/2.8, ISO 1250 & 13s shutter speed. I have a wired cable release, I just leave it to always on, so it takes one photo after another. At 13 seconds, the stars haven't moved that much to be visible at 14mm. If you want to use that same shutter speed, you'll need to double the ISO as your 17-40 will leave you with f/4. The noise does clean up pretty well though for night photography, so you can probably get away with it.
I recommend going out and taking some test photos of the stars this week and perfecting the technique. This should get you started. I have a Zeiss 21mm f/2.8 lens I'm going to try out and see if I like that lens more than my 14mm for night photography. I should take it out tonight and get test it before the meteor shower.