<human>: Condense the text into a few key points

I'm[18M] going to an amusement park/beach on Thursday with my best friend[17M], his GF[16F], and this girl I met a couple weeks ago. We became friends and hung out for several hours, but I immediately started to like her. At first she said she couldn't go but I insisted she should so I wouldn't be stuck alone with just my friend and his GF, she agreed. 

We have become fairly close friends in these past few weeks so I think I need to make it really obvious how I feel about her. I also don't want to do it too early in the day so that it becomes awkward if she says no. Or even if she says yes it could drag out and we could be cramming too much into a first date. 

How should I tell her? When should I tell her? Right now my only plan is to, about 2h before we leave, tell her "I really liked being around you today, what about you?" or something like that. Should be dropping hints throughout the day?
<bot>: Me, my friend, friend's GF, and a girl I like are going to an amusement park/beach. I need a game plan.