That will be up to you and your opponent. The way it's worked in previous tournaments is that you have a week or so to complete your match so you arrange a time with the person you're fighting ahead of time. If you're a chat regular it's as easy as coming in, seeing your partner and saying "Hey, you want to battle now?" and they say "Yup, sounds good!" Otherwise you can always send them a message saying, as an example, "Is 2pm EST on Monday good for you?" If your opponent is in a different timezone they can do the math to figure out what time that is for them and if it's convenient they'll get back to you affirmatively. If not, they can counter offer until you both settle on a time.