When my contractions started they were 5 mins apart. i called the hossy and they told me to come in soon.
I wish i had stayed at home longer, this was one of the factors that lead to my c/s... you can not be in active labour for longer than 12 maybe more at a hospital before they want to do something... wont go into it all, but i wouldnt rush there if you dont feel any urgency.
Also of course depends on how long it will take you to get to the hossy - dont want to leave it too long either and have your baby in the car!!! or an unplanned Homebirth