Okay, Im stumped [solved]

[Heretic86]

Can someone explain to me why this happens?

In Set Move Route, using the Jump command followed by a command that causes the Event to turn works fine.
In Set Move Route, entering jump(1,2) as a Script instead of a command causes an Event to turn early.

Suggestions?

[Blizzard]

You need a wait command before the turn command.

[KK20]

As to why that is, just look at Game_Character 3 under 'move_type_custom'. You'll quickly see that the problem is because of these:

        when 14  # Jump
          jump(command.parameters[0], command.parameters[1])
        end
        # If movement failure occurs when [Ignore if can't move] option is OFF
        if not @move_route.skippable and not moving? and not jumping?
          return
        end
        @move_route_index += 1

        when 45  # Script
          result = eval(command.parameters[0])
        end
        @move_route_index += 1

Using the command 'Jump' will not add onto @move_route_index while a script call will no matter what.

[Heretic86]

As to why that is, just look at Game_Character 3 under 'move_type_custom'. You'll quickly see that the problem is because of these:

        when 14  # Jump
          jump(command.parameters[0], command.parameters[1])
        end
        # If movement failure occurs when [Ignore if can't move] option is OFF
        if not @move_route.skippable and not moving? and not jumping?
          return
        end
        @move_route_index += 1

        when 45  # Script
          result = eval(command.parameters[0])
        end
        @move_route_index += 1

Using the command 'Jump' will not add onto @move_route_index while a script call will no matter what.

Exactly what I was looking for.  Index was being advanced and executed prematurely.