You can add vote/s to a Pro Webinar at anytime up to 5 mins to live. And it can be edited at anytime up to being run. Votes are added directly from the BrightTALK Presenter screen. Open the 'Votes form audience' tab and click 'Add poll for live audience voting'.
Note: Don't forget to enable the votes once you want to send out the votes to the audience.
Please view this full guide for more information on votes - "Votes - Pro Webinar User Guide_v2".
Note: Votes will be displayed on the presenter screen starting with the most recent vote that was added, and ending with the first vote that was added. Votes can be displayed to the audience in any order, as each is individually controlled.
Also don't forget to enable the votes once you want to send them out to the audience.