If your GPA is 3.0 or higher after the first semester (end of January) you can, if you'd like, take six courses during the following semester BUT keep in mind that there is no reason (in terms of graduation requirements) to take on an extra course and that the extra course that you take on will count as any other course - once you commit to taking the course you will not be allowed to drop it. You want to be sure that the work load isn't too much! You should also discuss with your tutor whether it is wise to take an additional course.
Please also be aware that taking additional courses will not shorten the time required to get your degree.