What Day Is P-Day?

I opened my email later in the evening the day we dropped Ben off at the MTC and squealed because I see an email from my boy titled-"I'm Alive" 😁
From Ben:
"Hey just got to send you a quick email saying I am OK. I love you long time and I will email you on P-Day. Hope everything is good and I will see you soon." 
Elder Nelson
I was so excited to know he is "Alive". That was never my concern with him just in Provo, but hey I'll take it. My concern was...he forgot to mention when P-Day was! This resulted in a very anxious , stressful ME checking my email EVERY day, ALL day long just in case. IT WAS A VERY CRAZY WEEK!