How do you know a woman is trying not to appear too eager via text but she still sees you as a possbile boyfriend?

I suggested an interesting event was coming up and she suggested we'd be going together. This happened over text since we do not see each other that often. When we texted about the event, she saw my messages and replied within 10 minutes. However once the day was set, when I sent a text about something practical she waited hours to open and read it. My last text was about something practical and a bit of funny flirting as well to which she replied with lol a smiley and something like see you then. Is she still into me or not?
How do you know a woman is trying not to appear too eager via text but she still sees you as a possbile boyfriend?
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