Traditionally, UCB classes start 10 minutes after the indicated start time.
http://summerenglish.berkeley.edu/2018/02/28/did-you-know-berkeley-time/
http://visit.berkeley.edu/attending-a-lecture-at-berkeley/
The MWF 12 lecture of MATH 1B is in Li Ka Shing, which is on the west side of campus, and further from Wheeler than Valley LSB. Distance is about 0.4 miles, but uphill. The student should be able to calculate whether 10 minutes is doable based on walking/running speed.