Grades are updated hourly so they are very accurate. For parents or student's wanting to check a student's work allow one hour from the time work was submitted, then review the grade by selecting the blue Quick link labeled "Student Portal" from this support site.
If homework was just submitted, within the hour a note of "Grade Pending" will appear until the teacher has graded the work. Give your teacher 48 hours to grade any written work.
You can always discuss with your grades at any time with your teacher.