We need to restrain our desire to be in contact with that person...
Its very common that right after the girl gives a man her #, the guy texts her or calls her, either the same night or the following morning.
Usually for the sake of keeping attraction or get an interaction going, but we must not feel obligated to do so in order to build attraction... We must learn to look at the big picture.
Talking to her the following morning will probly get an interaction going and yeah, it might help keeping the attraction that was built last night, but sometimes this works against you depending on the girl...
Many girls don't like texting much, instead they prefer meeting in person, or at least dealing with guys who are more willing to ask them out, even if they are going to say no, than dealing with guys who are in love with their Cell phones.
Ok you already know that.. So think about it, maybe your HB is not too much into keeping text interactions going for long.
In your case, given the short amount of time thats passed since your last text I wouldn't be scared or even worried. If you both had a good time and you built enough attraction the night you met, she will get back to you
Now, if you think you should really really contact her in any way, I'd recomend waiting 2 days (at least 1) and calling her to set up a date, or at least to say hi (If you want to be straight, call her; avoid texts for a while. Think of it as a comunicational experiment)...
Remember to keep things friendly, not talking too much (wearing conversation topics out), being funny, etc..
About the reopener, BITmixit gave you a good one that you can also use in Phone conversations "Chinese or Pizza"....
Another one I use (I know many guys use it too), is:
"Hey girl Guess what....... You just got lucky, Im in town and we're going for chinese/pizza/drinks/whatever........ You can have me for the evening..."
