You need to call precisely 72h ahead of your flight. Unless your flight leaves at Thursday night at midnight, you called a bit too early. Also, even if no instant upgrades are available, you should still have been added to the waitlist. You should now be at/near the top of the list (although any later Super Elites will bump you from that position). If you flying on an A320 you have a slightly better chance that the B767 to secure an upgrade.