I think it's great that you want to go straight into mentoring once you graduate. I have several students on my team now that are just dying to make the transition but I'll share the same advise that I tell them:
School comes first, then robotics.
Speaking from experience, once I graduated high school, I wanted to jump right back in and mentor. Problem was I was 250+ miles away so it wasn't easy and I was having HUGE FRC withdrawals. (So much so that a friend and I started a team here my junior year
) The way I handled it (and still help out today with my first team) is by doing a lot of email communication and Google+ Hangouts. It keeps you in the loop, allows you to give feed back and also allows you to focus on other things such as school. Freshman year of college is not easy. Everything is new, depending on if you go away to school, your lifestyle will change. It's best to get accustomed to school the first year then try to slowly get back in to the FRC lifestyle. If you are able to go back and help, do it on holidays or weekends when things at school aren't stressful. The biggest mistake a mentor-student can make is since they are just removed from the student role, they want to jump back in and help. You have to remember that it's the next set of student's turn to experience what you did as a student.
This past season we had a student go through the student-to-mentor transition and we made it easy for him. We had enough mentors and students with previous experience that help from him wasn't needed as much as he thought. We were glad to have him come back and help the team and it was a huge benefit for us but the last thing we would want for him is to go back and tell his parents that the reason his first year of college was so bad was because he was working with the robotics team so much, it took away from his studies.
The transition though is tough. You just have to change your mindset. It's ok to help out and work on somethings but remember, you're a
mentor and the mentor's purpose is to guide the students and be of assistance.