Marking is pretty easily corrected, a "Ah!" and redirection shiould work. There's a difference between marking and just lifting the leg as they pee though, just so you know
Delgado was neutered at 10 months and I can count on one hand the number of times he's marked and a few happened even after being neutered
He still pees 99.9% of the time with his leg up, even just standing in the middle of the yard
Neuter when you're comfortable but just for marking once I wouldn't hurry to do it.
Each dog is slightly different, Delgado started gaining the heavier chest and ruff around 8 months and he's still growing out at almost 2.
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010