I return again, with yet another question.

This time, I'm trying to get the player to enter the fighterbay of a destroyer only after a certain event is satisfied. At first, I thought the setup might fall under something like this.
Event Name
-when
--and
---is-event-true-delay
----Some Event
----0
---<=
----distance-ship-subsystem
-----Alpha 1
-----Some ship
-----fighterbay
----100
--Do something
I'm afraid that if the player gets within range of the fighterbay before this event is supposed to trigger, then exits the zone before the 'Some event' returns true, the second 'Some event' returns true, the entire expression will return true, which is not the intention.
So I thought about using and-in-sequence, but thought that this might break as well. If and-in-sequence returns false if even one of the events returns true out of order, then if the player gets in range of the fighterbay before the specified event returns true, then this event won't ever return true, thereby breaking it again.
I'm not sure if if I'm misinterpreting what these SEXPs do, or whether or not I should be looking for something else altogether.