You have time, theres no need to get anxious over this. When plants get badly rootbound the roots aren't just coming out the bottom, they are literally nothing but a mass of roots filling the entire pot. You can transplant now, 1 week, 2 weeks, maybe even 3 weeks. A rootbound plant will use water much faster than a non rootbound plant will, so when you notice a change in how much water its using thats a good time to do the transplant.