Five minutes in the penalty box. Just kidding.
Those charts are a starting point only. I have always found that using the recommended time produced ugly, flat, difficult negative and prints. I would try and narrow down the development time by increasing it excessively (either %150 or %200 of the recommended time). Depending on how the recommended time turns out.
Say for example the recommended time is 10 minutes, but this time produce flat prints. Double the development time (20 minutes), and this turns out to be too much. Your highlights are totally unprintable and the overall contrast is way too high (you need a grade 0 or 00 filter). You have just surrounded the optimum development time, and can usually rely on intuition as to whether the correct time is closer to ten or twenty minutes. The next step is to develop for the time intuition tells you is correct. The name of the game here is narrowing down the time as efficiently as possible. So rather then slowly creeping up on the correct time, you intentionally over develop in order to set the boundaries. This is a very intuitive approach, so if you are relatively new have either your teacher/mentor/fellow APUGers help you determine the correct time, that is what they/we are here for! It may take a few rolls (3-4) to find the best time, but when you do it will be well worth the effort. And making better prints will become incredibly easy.
Finally always use print quality as a gauge for development time, rather then charts and densitometers. The print is what matters, not how the negative graphs!
Best of luck!