why does harry start seeing the thestals from the 5th book?

I always took it as he doesn't remember seeing his motherdie, considering he was only one.
However he saw Cedric die right in front of him, so thats why he can the Thestals

he hasn't seen his parents getting killed, at least not james... lily was in his room when voldemort entered and killed her but i'm not sure that that counts cause harry was only one год old.. we don't know if he was sleeping или looking in another direction when his mother was killed.. and i'm not even sure he realized what was happening so that's maybe why he hasn't seen the thestals from день one at hogwarts...
he has seen cedric dying in the forth book, he was looking right at him and was very conscious of it..
at least that's what i think =)

Honestly, I'm not sure they thought that through. B/C Ты do have a point. But in the movie, Lily was by the door and Harry was facing the window. James was already dead. The book gave no decriptions on that note. So that's my best answer.

I always though that Harry just didn't understand what was going on and that's why when he saw cedrik
dying he realized what he saw so that's the reason why he sees the thestrals in the 5th Harry Poter book..I think so...

He sees them bECAUSE IN BOOK 4, THE GOBLET OF FIRE, HE SEES CEDRIC DIGGORY , PLAYED BY ROBERT PATTENSON, DIE TRYING TO SAVE HIMSELF FROM VOLDEMORT. AND STRANGLY ENOUGH NEVILLE LONGBOTTOM SAW IT TOO....

<<<<< Probably because he was just and wasn't aware of what was happening and can't remember the incident plus we saw in the movie when voldemort killed his mom he was in her arms so he maybe didn't really eye witnessed the exact секунда of the mother dying hope Ты understand what i'm trying to say i'm not really that good at explaining myself ^_^ >>>>>>>.