Contraction timing

blushingbride_08

I am confused with how long contractions take to get more intense and when I should leave for the hospital.  My doc said to call when the contractions are 5 mins apart, lasting for 1 min for an hour.  However I live about 1 hour from the hospital without traffic.  Will the contractions start around 5 mins apart or will I have enough lead time (like hours in advance that I will know I am labor) and can plan accordingly when to the leave for the hospital?  I'm confused and obviously a FTM. Typically how frequent are contractions when they first begin?