The IB has two exam sessions, which is an important difference from the single sitting of AP. The student does not choose the session, however; the school's academic calendar decides.
Two sessions, two hemispheres
The May session follows the academic year in the northern hemisphere and the November session that of the southern. Almost all schools in Turkey sit the May session.
In practice there is therefore one session for a student in Turkey, and November comes into play only for retakes.
When results are released
May session results appear in early July, November session results in January.
The July date is critical for the application calendar: whether conditional offers have been met becomes clear that day, and clearing processes run immediately afterwards.
How long the exam period lasts
The May session spreads over several weeks. With six subjects and multiple papers per subject, the total number of papers can exceed ten.
This produces a different fatigue from AP: rather than a compressed fortnight, a sustained pace across several weeks.
Retakes
One or more subjects can be retaken in a later session. The total is updated and the diploma reassessed.
A retake can mean losing a term against the university calendar: a November result comes out in January and misses most application cycles.
Where the calendar sits in planning
Internal assessments and core submissions fall months before the exam period, and the real crunch is there. A plan that reads the exam calendar and not the submission calendar misses the busiest part of the year.
For that reason the yearly plan is built backwards from the first submission date, not from the exam date.