When you schedule a planned exam it's the local time zone setting on your computer that will apply to the planned exam. Most computers today will automatically adjust the time zone settings for you, but that's not always the case. Therefore, be sure to check the local time zone setting that are set on your computer before you plan an exam so the exam doesn't start at a different time than you had planned.
The time that's shown to the students that tries to start a planned exam before the exam is active will be converted to the local time zone settings on the students computer.
In the examples below the times will be shown by the UTC standard which you can find more information about here.
A teacher that's located in Sweden has UTC+1 configured in the time zone settings and schedules a planned exam that will start at 2:00 p.m. the same day.
One of the students taking the exam is from Japan but currently in Sweden to write the exam. The student has forgot to change the time zone setting to Swedish time on his computer and still have the Japanese time zone setting, which means UTC +9. So, for this student the DigiExam client will show that the exam starts at 10:00 p.m. even if the student is in Sweden.
Because the exam is scheduled to start at 2:00 p.m. UTC +1 the student will be able to start the exam 2:00 p.m. UTC +1 even though the DigiExam client says the exam doesn't start until 10 p.m.
If the student had been in Japan instead of Sweden, he would've needed to start the exam at 10:00 p.m. Japanese time (UTC +9) since that's when the time in Sweden would've been 2:00 p.m.
A teacher is at a conference in New York, US with UTC-5 set in the time zone setting. The teacher schedules an exam that's set to start at 12:00 p.m. five days from now. When it's time for the students to write the exam the teacher is back in Sweden to monitor the exam.
All students have Swedish time zone settings on their computers, which means that when the students try to start the exam at 12:00 p.m. UTC +1, the DigiExam client will show the students that the exam doesn't start until 6:00 p.m. because the time isn't 12:00 p.m. UTC-5 yet, in New York the time is 6:00 a.m. when the time in Sweden is 12.00 p.m.
The teacher now needs to go into the planned exam and manually activate it so the students doesn't have to wait for six hours to start writing the exam.