I prefer texting because it minimizes guesswork. Each person has a written transcript of your exchange, so if you set a date for a definite time and a definite place (the address, specifically) on a definite day, there's no need for you to confirm with her. She has it written down, and if she has an appropriate interest level, she will refer back to the details as she prepares for the date.
By text, it has to be a specific date, place, and time that you set, and that she confirms with a "Ok," "Sounds good," "See you there," etc. If she doesn't respond when you set a date, time, and location, your schedule is still free as far as I'm concerned. I've had that happen, and girls get in touch the day of or the day before to cancel and I'm like, "Ok." Or I'll say, "I never heard back so I made other plans, no prob."
The point is that it's in writing, and it's going to stare her in the face. Words in verbal phone conversation have a way of changing over time in memory, and when I'm trying to set my schedule I prefer we both know exactly what was said and agreed to.