I have always wondered since I read hpatgof and how that it is the first time Harry can see the thestrals but shouldn't he have been able to see the the thestrals since his first year bc the first time he saw death wasn't Cedric it was actually his Mum and even if couldn't remember it he still should have been able to see the thestrals bc he still would've known and if didn't then in his third year he should have been able to bc he was having recollections of the memory restored to him by the dementors