I usually don't mind which event I start competing on. Sometimes I like starting on bars, only because that means that vault is the last event, and vault comes easiest to me so it's sort of like the cool down event. Then sometimes I like starting on beam because it's best to get my hardest event out of the way first. But a lot of times, I don't like starting on beam because I tend to be very nervous on beam and I can usually even see the beam shaking so it's bad. Sometimes I like starting on floor because I really love my floor routine and it's sorta like the great start to the competition.
So it usually depends on how I'm feeling, but I think I normally end up on bars first 90% of the time.