From Harry Potter and the Goblet of Fire:
“I have my reasons for using the boy, as I have already explained to you, and I will use no other. I have waited thirteen years. A few more months will make no difference. As for the protection surrounding the boy, I believe my plan will be effective. All that is needed is a little courage from you, Wormtail — courage you will find, unless you wish to feel the full extent of Lord Voldemort’s wrath —”
Was Voldemort’s plan always to wait for the final trial of the Triwizard Tournament? It seems rather contrived and dependent on good luck. (See here and here.) Wouldn't it have been easier for Voldemort to merely ask Crouch/Moody to abduct Harry at some point? It seems more likely to me that Voldemort's plan was merely to get Moody as a teacher, and then to let Moody wing it from there.
Is there any canon evidence whether Voldemort's scheme was micromanaged and planned from the beginning, or was the third cup Portkey merely decided on later on, when Moody realized Dumbledore was watching him too closely to disallow an easier alternative?