Your facebook link does not work.
Anyway, there are several websites that offer advice.
I'm a newbie also, but by what I have learned - at about two months (if they are mainly IB) the feather shafts on the chest will be whiter on males and the pattern will be more dilute (I believe feathered was the term used) on females. Google is your friend, search for "sexing my peacock" and see what you get.
My own two cents: I used to have chickens, it was fairly easy to tell the males after they were a few days old, thump them on the chest and see what they do. The females cower and run, the males are ready for a fight. I have two peafowl from eggs purchased from
ebay. The first is 5 days old now, the second 2 days. The first is very likely male, full of spunk and ready to fight with anything, the second is more reserved and cautious, likely female.