Well my opponent sent me a pm first duel day I believe and I replied, either that day or the next and haven't heard back since, I was planning to do the fight Friday, but the lack of a response worries me. Any suggestions?
Since matches only started about 12 hours ago, give them a bit more time to respond. I'd probably give them at least another 12 hours before I worried too much. Maybe send them another PM.
Also, make sure your mailbox is set to save outgoing messages, so that if the match ends up not happening, you can show that you tried to make it happen. This applies to everyone really.
If you don't hear from them in the next 12 hours, PM one of the warmasters.