When should I text her on Facebook ?

I was at a school trip one week ago, and I got to meet this girl. She stayed in my bed overnight and it seemed like she likes me. I didnt add her on Faceebok till tuesday (that is 5 day difference from the trip). I thought she forgot about what happened at the trip, but yersterday at school she suddenly popped up behind me and put her covered my yes with her hands. We talked for a while and then she had to go home. I saw her once today and we said said hi to each other. Should I text her on fb, wait, or give up ? Thx...