Hi, Unprotected vaginal sex is a risk. If he is positive but undetectable it lessens the chance of infection but it is unreliable. You had a risk and will need to test.
You can test at 4-6 weeks for a baseline result and again at 13 weeks to confirm your result.
I completely agree with Ftworthstress76137, I'd like to add that any HIV test is conclusive if taken 12 weeks after an exposure, but you can take them before that, 3rd gen will give you an excellent indicator about your status around 6 - 8 weeks after exposure and 4th gen 4 - 6 weeks after exposure.
A result given in those times is very unlike to change, but only a doctor, based on your risk level and his experience could advice you to skip the confirmatory test after 12 weeks post exposure.
Hope this helps.
About it odds you were asking for, they're way lower than the ones you would get by having unprotected intercourse with an HIV+ partner without treatment or without undetectable viral load. The probability is exceedingly low, and recent studies show that is close to zero. But a small risk is still there, that's why testing is advised.