My personal favorite spot to photograph sunrise on Mt Assiniboine is a small pond in the swampy area one crosses on the trail to Nublet Pass. It's waters are usally calm and mirror like while the larger surface of Lake Magog is rippled most days at sunrise. The shot above shows my wife set up on this pond at first light.
Mid to late summer is the best time of year to photograph Mt Assiniboine. If I had to pick, I would say the last week in July and the first week in August would be the best time to photograph the Assiniboine area.
The above photo was taken with a focal length of 35 mm on a 35mm full frame camera.