Your first text should say what ever you want and more importantly WHENEVER you want! you should never put a timescale on texting a girl after meeting! the one rule i live by is text a girl when i feel like texting her. that could be 10 minutes after meeting her it could be 2 weeks! i have never had a structured text to send a girl because you meet every girl in completely different situations.

Be yourself! Text what and when you want. if there is no response the initial face to face interaction wasnt strong enough and you didnt make a strong enough connection. if you made a good connection with her and you were both feeling it she would text you back no matter what you put!