Since you got the camera and housing together, hopefully they've been well depth tested. I bought a G12 and housing separately. The G12 was used, but from Craigslist, so I got to inspect it before buying. It was in mint condition. The housing was bought new from eBay. It was also in mint condition - sealed box. The first thing I did was put the housing in 1' of water for 24 hours. No leaks. When the trip finally rolled around, I took the housing, empty, on the first dive. It leaked! Ah, maybe I didn't seal it properly? I cleaned it, inside and out, and rechecked the o-ring. I tested again the next day and it leaked again! I ended up using my backup GoPro Hero 2 (lower quality) for the rest of the trip.
Some things I learned:
1. New doesn't mean it'll work as expected.
2. Using tissue paper to check for leaks made a big goopy mess in the housing. Use paper towel instead.
3. Just a teaspoon's worth of salt water leaves a lot of salt crystals in the housing, so rinse and dissolve the inside before drying.
Canon specific:
4. No warranty on accessories. If a product, such as an underwater housing, fails to perform as advertised and ruins a camera, they'll replace the camera but will not fix the housing. (I actually sent in the housing to be inspected for repairs and it went from West Coast->East Coast->West Coast->back to me!)
5. For the WP-DC34 housing, there are some pretty bad ratings on Amazon (~25%) that points to leakage issues, even when new. The culprit is some excess mold lines along where the o-ring seals. (There's a webpage that talks about this and details a fix, which I've implemented and it works - tested to 27-28m.)
Enjoy your rig!