This depends on the course and the instructor. To start, you should login to Blackboard on the first day of class to access your online, hybrid, live remote, and/or flex class(es), view the syllabus, and complete any assignments due during the first week.
During the first week, carefully read the information available within Blackboard and check the class syllabus to determine how often your instructor expects you to login and work on the coursework. In most classes, students should expect to login once per day or several times per week to check for class announcements and make progress in the course.