We traditionally add the spices at the begining in the hot oil but not if there is going to be onion or garlic in the dish! Those take so much time to fry up so the spices will burn. If using any whole spices like cumin seed, cloves, cardomon, add them to the oil first. Also, garam masala should not be added to the oil, it doesnt retain any flavor that way..it is always supposed to be added at the end of cooking a dish. many dishes in cookbooks specify to sprinkle with garam masala after cooking.
Payal