First job out of college. How long should i stay at this job until I find another one?

The job i have right now is the first steady permanent job since ive been out of college (graduated with an ociates degree w/ degree in office administration). I have been working there since april of 07. I started as an accounts payable clerk/istant and about three months ago, I was "promoted" to an administrative istant. The job really doesnt pay that well. Nevermind the experience, i need the time on my resume to show that I can hold a job for a certain amount of time. I did temp work and long term temporary inmgnets for about a year and a half after i graduated. this is my first stable job. i want a job with a little more responsiblity and much better pay. (i am making 13 an hour now) how much longer should i stay here and from what i explained, what type of salary should my range be. realistically from my experience, very good skills and the type of degree i have (specializing in admin work) i would like to be making btwn 35-45k. this is in new york city.