Hi, do you put Moleskin on where you think you may develop a blister, before going to the parks? Or do you wait and see? If something is starting to get sore do you put it on then?
If you have an area on your feet you know (from past experience) might be a problem, I would put it on in the morning. Cut a few more strips to carry with you, and add them right away if you feel a sore spot developing somewhere else. I tend to develop blisters very easily, so moleskin is a staple for me, even at home.
Also, be sure to wear shoes that are broken in! Even sneakers can cause problems when they are new.