Three days is a bit long to wait in that situation.
This is a pretty straightforward guide to asking a girl out on a date by text: http://www.girlschase.com/content/how-text-girl
When my texting game sucked, I thought it was invaluable.
Basically, you want to have the following elements in your initial text:
1. The girl's name.
2. Some new information.
3. Consideration, something that shows you are thinking about her/care about her.
4. A command.
5. A greeting.
6. A date request.
So something like:
HB! Hope your weekend was good
I cracked a few beers & put on the DS9 second season at my place. Hey, there is a party at ___ on ___ night! Let me know if you can make it.