Remember that a lot of orientation will be pretty useless. Honestly, i'd look it as a blessing to have an excuse to get out of orienation or at least some of it. How many welcome speeches do you really need to hear?
I would talk to your academic advisor and find out exactly what is going on at orienation and what you could miss or not miss.
And for the previous poster, the reason there's 18 events and 15 hours is because there's probably 3 breaks mixed in there or something.