If 15 minutes is the normal time, and your film is underexposed by 1-1/3 stops, plus a probable 1/3 stop more that can be assumed in many cases due to working EIs not matching box speed, plus maybe another 1/3 stop due to using Rodinal vs. what the manufacturer used in their testing, for a total of two stops, I don't think 17 minutes will be enough time to push contrast to a "normal" level. If your film can even reach +2, it will probably take 150 to 200 percent of the normal developing time, based on my experience with D-76 and HC-110. Rodinal may be different, but I would develop for at least 23 minutes, if I had to make an educated guess.
That is just the general answer. It does all depend on the contrast you want on the neg., however. I said what I said above based on the idea that you just want to develop your film to normal highlight densities without any special processes.
You may decide, for instance, that for the prints you want, or the way you like to print, and if the light at the scene was high in contrast, you would rather work up from a flatter neg. Thus, only push one stop, or even no stops.
You may also decide that to minimize grain, you want to push only one stop, then tone the negative in selenium toner rather than pushing two stops...or push no stops and then tone.
In order to answer the question for yourself, you need to think about the lighting in which you shot, the prints you want, how your Tri-X responds to light, and where your exposure placed all the tones at the scene.
