The wedding ceremony has already taken place, and to add to that have ever heard of the bride not being invited to her own wedding feast.
The oil is being used symbolically here, then the principle of Expositional Constancy demands that it represent the Holy Spirit.
So the conclusion is that the 10 bridesmaids are tribulation survivors.
I have thought that for some time.
Reading that one day, it occurred to me that the Bridegroom was marrying the Bride, which is believers, who are not the attendants.
I was trying to figu out who the virgins represented but you answered that well.