If you can find out about the course, leave a bit of time for any hills or inclines, catch it up on the down.
It may not be a PB type course also.
Other point, its tempting to go out fast but more likely to get injured earlier or have to slow by time you saved anyway maybe more.
Go out slower and increase pace gradually, with a bit of wiggle room for inclines... I always try and leave enough so my last mile or two are my fastest, and finish with a sprint to the line.
Did this 4 weeks ago and knocked 4 mins off PB... Last full mile was joint fastest with 3rd or 4th, and finished the last bit with fastest pace of the entire race.