Ah, but Dear Voldie was already in the Horcrux business. If he went to Godrick's hollow with the intent of killing off the Potters and creating his final horcrux, he would have done all the preparations necessary.
One more thought, Suppose there is a threshold of soul needed to keep a person alive?
Voldemort may have tread too close to that edge with his 7th horcrux, and that is why it took over a decade to recover enough to become even minimally active.