Here's a great chart that shows you how much to read each day in order to read the entire Book of Mormon starting on June 9th and finishing by August 7th. If you'd like to change the dates on the schedule, you can email me at email@example.com and I can send you the PowerPoint file so that you can edit it.
My friend at church designed this challenge (and cute schedule) for her Primary class. I'm not sure if my Primary kids will do it, but I sure am. I think this would be great for teenagers to do on their own as well.
I made another version where instead of reading that much per day, it is on a weekly basis. It would take 59 weeks to read the Book of Mormon on this schedule (a little less than 14 months).
After several email requests, I also made a generic daily reading chart. Here ya go.