We need to see the soil. Simply coming out of the bottom quickly doesn't necessarily mean good drainage. Many water retentive media will pull away from the sides of the pot causing water to pour out the bottom which then results in overly dry conditions.

Sometimes wilting can be both from over and under watering. So you have to figure out which it is. Also plants will wilt in strong sun or heat, and they will recover from this. It has nothing to do with how much or little they are watered. I don't suspect this in your case though.
I think the well drained soil means use a potting mix, not garden soil. Which is good advice. I have cestrum plants, which are often called Jasmines, but they are different. i have one Jasmine. The cestrums are easier to grow. My Jasmine got a bad case of spider mite last winter, still recovering. Seems to possibly picked up a virus from the mites, as it has never really recovered yet from the attack.
My cestrums were right next to it, but the mites left them alone.

This post was edited by Drew51 on Tue, Jun 3, 14 at 8:30

Thanks to you both. I think the answer is a combination of things- I think the potting mix they plants came in was extra well-draining AND I think the sun was making them droop.

For the moment, I have them stabilized. I put worm castings atop the soil and that seems to help retain some water. Additionally, I am not so quick to water them when they wilt- but instead wait until evening to see if they perk up.

Thanks again...

Sounds excellent, the plant will love the worm castings. I love using that product!
Mine is growing again, but it was in limbo for months. I didn't see the mites, and they really sucked the life out of the plant. I will spray before I bring it in this year.