Need help to decide when to give my two weeks notice.?

Ok, so here's the deal. I currently work at Old Navy as a service and training manager. I hate my job. like it literally makes me sick to my stomach, vomiting almost every morning from the anxiety and nervousness this job gives me. So, consequently i've been applying to different jobs like crazy!!! looking for something completely out of retail a more 9 to 5 type job that will be much more like what I'm looking for. I was selected for an interview at The Ohio State University for a position in revenue cycle as a rep. i just had the interview today, but i know i did very well and had an answer for everything they asked. After the interview, they sent me across the street to do a background check as well (which costs them money to do, so they wouldn't have sent me if they didn't think i was most likely going to be selected, correct?) Well here's the tricky part, i won't know until Friday whether or not i got the job, but the HR rep whom i interviewed with said that there will be a training cl December 7th that they are trying to get all new hires into. So do i want to give Old Navy my two weeks as soon as i find out i for sure get the job?- this meaning that they will probabaly schedule me on the 7th and i'll have to call off to make it to the training at Ohio State. OR do i give my two weeks notice now and risk being out-of-work for a while, but know i will have that time free for training? Keep in mind it's the holidays right now and even if i didn't get the osu position i could find a part time job anywhere right now for retail just until i found something else (which i have years of experience in). I also have a bachelors degree in communications from the Ohio State University and have held two other jobs there while at school, one an internship the other a resident advisor, so i'm pretty certain i'll get the position, but i also don't want to really screw myself over. But, on the otherhand, i hate this job so much, that quitting would give me the push i need to get my career going in the right direction and wake me up to what is important, a life, and right now my job has become my life. PLEASE HELP ME!!!!!!!! i need advice, support, and personal experience references!!! HELP ME HELP ME!!!!