Is this Confederate star jasmine, Monica???

Look at the tag for the name of the plant. Hopefully it will have a label listing the Latin name so you know exactly what you have. Go online and look up mature size, cold hardiness and pros/cons of plant for what you need. With the latin name or a picture people on this forum can tell you how it actually grows here in TX.

If it's Star Jasmine that you're considering -- it's a wonderful plant and would be perfect for an arbor! Just be sure you get the Madison variety as it is VERY freeze tolerant where the regular one is not.

Here is a link that might be useful: Discussion about Star Jasmines freezing ...

Madison Star Jasmines will eventually grow into a very large evergreen vine, but if I wanted good coverage soon I'd plant one at the corners and then space them every two or three feet and guide them upwards as they grow. I'm guessing in three years it should be to the top of the arbor, but it will be blooming those fantastically fragrant blooms for you next spring. The saying for how perennials grow: the first year they sleep, second year they creep and third year they leap.