Mark 14
 
As Peter was below in the courtyard, one of the servant-girls of the high priest came,
67 and seeing Peter warming himself, she looked at him and said, "You also were with Jesus the Nazarene."
68 But he denied it, saying, "I neither know nor understand what you are talking about." And he went out onto the porch
69 The servant-girl saw him, and began once more to say to the bystanders, "This is one of them!"
70 But again he denied it. And after a little while the bystanders were again saying to Peter, "Surely you are one of them, for you are a Galilean too."
71 But he began to curse and swear, "I do not know this man you are talking about!"
72 Immediately a rooster crowed a second time. And Peter remembered how Jesus had made the remark to him, "Before a rooster crows twice, you will deny Me three times." And he began to weep.
So when did the rooster crow the first time??
besides, it sounds like the other Gospel accounts suggest that the rooster only had to crow once, for Jesus words to come true....
 
Lk 22
And Peter remembered the word of the Lord, how He had told him, "Before a rooster crows today, you will deny Me three times."
 
Matt 26
75 And Peter remembered the word which Jesus had said, "Before a rooster crows, you will deny Me three times." And he went out and wept bitterly.
Jn 13
Jesus answered, "Will you lay down your life for Me? Truly, truly, I say to you, a rooster will not crow until you deny Me three times.