From the time of exposure to when the spots appear, it is about two weeks. Someone with chicken pox is most contagious before the spots appear - once the spots appear, it's basically safe for anyone to be around you.
I never managed to get it during school, even though one year, almost everyone in my grade got it. Then a couple of years later, I kissed someone who came out with their spots two days later, and I still didn't manage to get it!
When I started teaching, I had a few freakouts - mostly, I'd teach the kids, then two or three days later, the mother would call and say, "I hope you've had the chicken pox before because so-and-so just came out with his spots today"
After a couple of years, I paid for a chicken pox vaccine to avoid all the worrying. If you don't get it this time, I'd recommend you get the vaccine once you're over your cold. Your GP will write you a script, and it's not that expensive to get it at the pharmacy. You only have to pay for the vaccine if your GP bulk bills (since you're a student, you should be able to get a health care card and be bulk billed).
Topic: chicken pox