It's your choice, really. Some people say you have a chance of getting your visa processed more quickly if you get it done in advance. But if you choose to do that and they do take longer than 12 months to process your visa (current average is 13ish months) they might request that you get it done again. It's a gamble.
Original Nationality: US
Visa #1: PMV (300) through Washington, D.C
Applied: April 2013.
Visa Granted: January 2014.
Visa #2: Subclass 820 (From PMV).
Applied: End of April 2014.
Visa Granted: Early July 2014.
Visa #3: 801 (PR)
Eligibility Date: End of April 2016 (Applied a month prior).
PR Granted: Early April 2017.