Excellent. At 0x244D7, put F4 7F. This changes the destination of the jump to different code when you press the Y button aboard the Epoch.
At 0x27FF4, put AF 62 28 7E D0 03 4C C7 45 4C 09 45. This will check 7E2862, and if it's not 0, cancel opening the menu.
In your events, you'll want to write 0 or 1 to 7E2862 as a 2-byte value when enabling or disabling the Epoch's time gauge.