TD, you don't have to leave any growing at the present time. What will happen is , you will see 3rd stage growth sprouting up here and there all season long, even if you have been pinching them off now. Once Sept starts, I just let the plant go. You can guide the new growth where you have some old battered leaves or just let it do what it wants. When I'm growing this new growth late in the season, I will sometimes pinch off the secondary sprouts off of those new vines, as I don't want too much new growth to take from the pumpkin, just my 2 cents.