All date and time information on your event landing page will adjust to the time zone of the viewer's device, so you don't have to manually calculate time differences when publishing your event.
Before pinning down the specific hours of the day you'd like to have your sessions, think about who your audiences are and what countries they will likely be from.
Normally, even with international audiences, there will be a certain timeframe that will work for most of them.
If your audiences are mostly from the US and Asia:
5-9pm, Pacific Time (which is morning in Asia) will be a good option.
If your audiences are mostly from the US and Europe:
8am-12pm, Pacific Time (which is evening in Europe) will be a good option.
If your audience have less flexibility with schedules, you can always remind them that recordings will be provided after the conference.