I started showing some very unconscious signs about a year or so afterwards, when my relationship with my dad eventually shifted quite a bit (I guess it might have even been earlier than that, now I think of it). Two-three years ago (which would have made it approximately 6-10 years after the event) I then told my boyfriend that I was extremely uncomfortable around my uncle when he visited, although I had no clue why it was such a bad feeling.
The moment I actually recalled the event, however, which triggered the PTSD symptoms from then on, happened only... 7 months ago? So this is a full 13 years afterwards, when I was at university, but likely to be due to the sudden extreme stress I felt, along with other issues. From that day onwards I've gradually become a lot more unpredictable in my behaviour, and now it certainly connects the dots, so to speak.