Jethrobee,
Sorry, you are incorrect - the others have it right.
18 months from the date of passing the first exam to passing the last. You then have 2 years from the completion of the last exam to taking the skill test and applying for the licence (I think the exams have to be in the validity period when the application is sent).
Interesting question - if you took your first exam BEFORE the period was extended to 18 months, do you have 12 or 18 months?
Jethrobee, you may still be right
SD