Explore Magic key

Any ideas how many explore keys will be available after released? I know only disney truly knows, but i have enchant and I want to upgrade but I have a reservation I wanna keep on Jan 31 (explore blocked). So they would go on sale January 13th, and I could upgrade January 31st at night. I don’t wanna risk missing out on this upgrade. I’m just wondering if they’re projected to have a high availability.