What "check-in page" would that be? Did you try the Aegean app? This isn't supposed to work on a desktop browser (laptop/PC/Mac or even mobile phone using the desktop version of a browser)...
In the app it should show up right away when you check your flight. Perhaps it won't activate immediately at 00:01 (sometimes even online check-in first becomes available 10 minutes past the T-48hours mark). But it should show up.