You should never be in a hurry because it will represent you as a desperate guy.
So before asking her out over text, talk to her for a few days.
Keep in mind that every girl is different. One may get comfortable in a week, and the other may take one month.
So wait for the right time.
On average, a girl takes two to four weeks to get comfortable. During this time, you have to show that you are the right guy for her.
If you do that, she won't reject your proposal.