The standard advice when potting plants into larger containers is almost always to move up by one pot size. There are, though, exceptions, and Campsis is one of them, primarily because, planted in spring, they grow rapidly and once it clings to a support, its then impossible to provide a larger pot later on. This plant should really be planted into at least a 15 gallon container, and the support you provide for it to cling to should be very strong, and firmly affixed to a wall, with a small gap between the trellis and the wall to enable the plant to twine round it.
It's true that two weeks is not long enough for your new vine to do anything much at all, other than putting out more roots. You don't say where you are, so it's difficult to say whether you should leave it as it is for now (because it might not do much before Fall/winter arrives) or, if its somewhere with mild and later onset winters, when it should be immediately placed into a larger container now, and the support for it to climb replaced immediately with something more suitable for a vine that is likely to grow 15 x 15 feet. There are smaller varieties more suitable for container growing, but you have said it is Campsis radicans - it will not achieve its full height and spread of over 30 feet in a container, but might well make 10-15 feet as described, although an even larger pot will mean larger topgrowth. May need protection if your winters are particularly cold. https://www.gardeningknowhow.com/ornamental/vines/trumpet-vine/trumpet-vines-in-containers.htm