"Until you actually know who's running, especially in each round, you can't vote effectively in advance. Some people did, not being NDP I'm not sure exactly how that process worked, but the idea was to see how it worked with people voting real time."
Advance voting was done via preferential ballot. You rank everyone in order of preference. If your first place candidate gets eliminated, your vote shifts to the next person still in the running.
It turns out that 85% of the votes cast were advanced ballots, so the people logging in to vote round round by round or who voted in person at the convention had a very limited ability to change the outcome.