According to previous posts I've seen in this forum, if you dedicate about 1.5 or 2 hours a day, five days a week, you'll take about one month and a half to finish reading entire K&B's book.
Of course you can increase your daily dedication taking some more hours but I don't recommend because most important than read entire book in a short time is full understand the samples and practice all the questions.
You must focus on quality time and not on quantity time. (This is the point).
Would be a great deal for you if you could take some mock exams. There are a lot of free and commercial ones. My recommendation is Marcus Green's free mock exams and Wizlabs commercial one.
You also can take a look at this forum where many other people have posted free mock exam list.
As long as your results are constant on exams you take, for sure you'll be ready for write the
SCJP's exam and get a good grade.
Good Luck and welcome to this forum.