Solved.
For anyone else experiencing this, the solution is:
1.Create a new Boolean variable, such as "IsConditionMet", and set its initial value to False.
2.Create a new event in your event sheet that compares the two numbers and adds a "Trigger once" condition.
3.Add an additional condition to check whether the "IsConditionMet" variable is False. This will ensure that the actions in the event only occur once when the condition is first met.
4.In the action section of the event, set the "IsConditionMet" variable to True, and add the actions to start the fade in effect.
Cheers! Happy game making everyone, who's browsing this!