The wondrous icon of Panagia Pantanassa, from the Katholikon of the Monastery of Vatopedi, Mount Athos (source)
On October 27th, 2014, at 4AM, the Orthros service began, and he went down to the Church, and having venerated the icons, went and sat down. The church had many people in it, and at the stall where he went, he sat next to one man, but the other side was empty.
He waited patiently, but the time was passing, and the monk had not appeared who would have led him to the confessor. Around 4:20AM, he turns around, and sees next to him, in the formerly empty stall, a nun! The nun approached him and said: "Wait, everything will go well, you will confess. Don't worry, just wait a little."
He thought that most likely, the large monasteries had some nun there to help in the church. A short time passed, and the inpatient man thought that he would leave to find someone to take him to confession. It was around 4:45AM when he planned to leave. He took a step, and again he saw the nun approach him, grab him by the shoulder, and lightly turn him back towards his stall. And she told him: "I told you to be patient and wait...Now the Six Psalms are finishing, and the monk will come to take you to the confessor for you to confess."
In reality, after two minutes, the monk came to lead him to the confessor. K.P. did not say anything to that monk because he was suspicious. In reality, when he reached the confessor, having spoken a bit, K.P. told him:
"It's good that you had that nun there to strengthen me to be patient and wait..."
"What nun are you talking about, blessed one? There are no nuns here. This is the Holy Mountain, women and nuns aren't allowed!"
"But, I spoke with her twice!"
The spiritual father replied: "You spoke with our Panagia, but you didn't realize it, my child!"
Then the confessor asked him to describe her. K.P. said: "She was tall, around 30-35 years of age, and very beautiful!"
(amateur translation of text from source)
Most-holy Theotokos, save us!