The time you take is irrelevant, assuming you enter your answers sometime during the week.
Final score is based on which puzzles you solved, and the top places are differentiated by some optimizer puzzles.
The puzzles are typically very elegant, all new types, and worth having a look at even if you're not competing seriously.
The format will be the same as last year's contest (of which I have fond memories).
Key differences from regular LMI tests:
• There will not be an IB (i.e. no Instructions Booklet)
• The PB (Puzzle Booklet) will not have any password
• After the contest starts, you can download the pdf and start solving. Login at the contest page to start submitting.
• There is no time limit. You can submit until the contest ends.
• There will be some optimizer puzzles.
• Same scores will have same rank (i.e. early submissions do not count towards rank)