NAVLE is only offered during two periods a year, from Nov-Dec and again in April. You must be within 10 months of graduation to sit the test, so the vast majority of students (those with a traditional four year program) are first eligible and take it during November-December of their clinical/final/fourth year. If you fail, you get another chance in April before graduation, if you fail that you have to wait until the next Nov-Dec period again which would be several months after graduation for your third attempt.