Had sex on what we think was last day of ovulation but it might of been a day or two later, i pulled out didn't cum, but we took plan b 30 minutes later are we good you think? and could you be good if you take plan b on day of ovulation?

Yes: Yes, regardless of where you are in your cycle or timing of ovulation, Plan B if taken within 72 hours of unprotected or inadequately protected sex will reduce chances of pregnancy (to less than 1%). The sooner you take it, the better, though Plan B is likely effective even as much as 5 days out. Of course it's safer to use protection during/before sex, but Plan B is a good plan b when needed.