Keeping the ball rolling
First, it will keep you from sitting there stewing and worrying and sweating because you'll be too busy having fun. Second, when she finally does walk in, instead of seeing you slumped over your fifth margarita she'll see you being lively and fun and social. She might even have to go steal you away from a group of women.
Hey, let them all fight over you.
Remember your abundance mindset. Even if she never shows up at all, you should still be able to have a great time. Then when she calls to apologize later, you can honestly tell her, "I was sorry you didn't make it, but I ended up having a great time anyway. Should we make plans for another time?"
Is the light bulb clicking on yet? Here is what happened. You are now Superman. You can walk into any situation and have a good time. You do not rely on any specific woman for you to feel good, confident, happy, and, well ... super. You know that you have the super power to meet women everywhere. That is a very great power. Use it responsibly. And have fun.
Why venue change is stressful
A weird thing happens when you get together the first few times with someone new. Each time, you feel like whatever progress you made the last time has been cut in half if not more. You take a giant step back in rapport and have to start building it up again. Why is that? Well, there are lots of reasons. For one, people are not cartoon characters, they are people, subject to moods, emotions, and all manner of change. So the next time you see her, she's not the same her you saw last time. Also, assuming you are getting together in a different place, that alone is enough to change the dynamic. Whatever you do, don't let this throw you. I bring it up so you are prepared for it. It's all part of the process.
So do you go back to square one? Sometimes, sadly, yes. But even if you feel like you're just meeting for the first time, that feeling will go away much more quickly than it did on the actual first time. You'll make faster progress, regain lost ground, and be back feeling comfortable again in no time.
Think about a good friend that moves away or travels abroad, so you don't see them for months. Then they call up out of the blue, announcing they've returned. You get together and, there are a few moments of awkwardness. It's just a human thing. Get used to it, and realize that feeling passes and things go back to normal.
This can actually be used to your advantage.
How? By doing a change of venue while you're with her. Say you start at the coffee place, then go for a walk outside, then stop somewhere for lunch, then go to the beach. It's like you've gone on four different dates.