If there are some students who you need to wait to move to the next school year, you can leave these students with no change to their enrollment in the promote/graduate task in Core.
In Core go to Users > Manage Student Enrollments.
This task will allow you promote or graduate your students into the next school year. When you select the appropriate year from the drop down menu, each of the grade levels will appear.
Once you select the appropriate grade level from the list click Promote. You will then be taken to a list of all the students that can be promoted. Next to each student name there are four radio buttons, promote, repeat, withdraw, and no change. For students who you wish to leave in their current enrollments, select the no change radio button.
When you complete the task, by going through all the steps, the students that were left with no change will be left on the promote list, and when/if you are ready to make a change to their status, you can return to the Promote task and run it again.
The Promote task can be run as many times as needed.