Take a look at polling location finder or the Northfield precinct map (pdf) to find where you vote.
Polls are open until 8:00 pm. As long as you are in line at 8:00 pm you will be allowed to vote (but to be safe, go early)
M-Th: 10am-5pm, 7pm-9pm
Sun: 1pm-5pm, 7pm-9pm