Hi hello this is my first reddit post so don't judge me 😅

So I [20F] am into this guy's [19M] who I've gotten to know better over the past month. However, because the mutual activity we share has ended for the school year, I never see him. We snapchat but he isn't quick to respond and I'm not sure how to keep a conversation with him. The school year is over in three weeks and then I'm going to be far far away for the summer. How do I establish a good relationship (friendship or more) with him before I leave?