my oldest was cocking his leg at four month the pup's 6 months and showing no sign of it.
He stands with his back legs on the patio step front legs on the garden, and aims looks hillarious

Our male whippet just started lifting his leg this week and he is just 9 months old

Angel was about 13mths when he started to cock his leg however he does still sometimes squat.

Mine started at 7 months to cock his leg. He still squats for a wee, but when just marking he'll cock his leg.

I remember vividly meeting a gentleman with his GSD while I was out with my own training her.
We began to talk about all things GSD while the two dogs played.
Anyway.....
After we had talked for a few minutes we noticed that my bitch and his dog were paying a lot of attention to an area of ground just in front (perhaps 12 inches) from a high wall.

As we stood and watched, my bitch promptly squatted and "marked" the area she had just been sniffing. The man I was stood with commented that his boy always "marked" just there every time they visited the field so we joked that in was probably the visitors book for all dogs as they entered or left the field, letting the other dogs in the area know who had been there lately.
His boy then did something quite unusual.
He performed a wheelie, stood up on his back legs and pee'd up the wall just like a human male stood at a urinal (ladies you might have to ask your OH how we do this...hehehehe)
As the dog finished his "marking" I commented to the man about how unusual it was to see a dog doing that. I also asked when he started adopting such an unusual stance.

The man answered "Oh he started doing it like that, the day after a wall fell on him"

Enjoy your dogs!!

Dave

I have a girly Lakeland Cilla who does this, she is the smallest dog in the house and I was always led to believe that when they did this it is to fool other dogs into believing they are bigger than they really are.

Well it might work on dogs visiting the area.

El Vez has done it a couple of times once at 3 months in the garden and this morning on a tree, me think it must have been a really smelly tree