How long after graduation can one afford a home in the city?

I'm just curious to know how long after a student graduates can he expect to be able to purchase his own home, should he choose to stay in OR very very near the city. I am thinking about my own future and I think I may have to deal with apartments for the rest of my life because once I finish school, I'll be up to my eyeballs in student loans and I'll have to make sure I get those paid off--seems like that would take up most of my funds, in addition to regular living expenses. I won't have to worry about having a car since I don't drive so I will save money in gas, car insurance, car upkeep, and car purchase cost. The only other little things I will have ot pay for besides food and utilities are landline, cell, and internet. I don't reckon I'll be having a family ANY time soon if at all so I'd be most interested in a house suitable for a single person + a guest (so like a 2br for an occassional visitor like family or friend). Since I would prefer to live in a city, I've given up hope for a backyard, but I would like a place that's just right if I want to have at least a medium sized doggy. What I'm asking is, how long do you think it would take to be able to afford a small house (NOT a condo!) in a city, after I finish gradschool? Is it just completely arbitrary? Is it entirely dependent on what kind of job I can secure after graduation? Is it more so dependent on which city I ultimately end up in? Is it impossible to purchase property before the age of 30 in a major city? What are good ways to become eligible for a decent mortgage in a major city? Ideally I'd like to get a 15 year plan so as to 1. pay it off sooner and 2. not end up paying 2x+ for the property in the long run. Is it possible to own a home in a major city on an accountant or CPA's salary? Thanks......>