i know the answer ✌️😎

Around 5ms: Change in tone-color (due to comb-filter-effect)
Around 20ms: Almost no audible difference (to my ears)
Above 30ms: From here, you can start to hear a difference between the transients of original and delay. Imagine this way: 30ms is the point, where you can just detect a tiny difference between the transients. From there, it increases. So around 70ms, to two signals will seem more separate.
Think about it this way: How far from barely noticeable is the gap between the transienst. Or as another approach: Are the two transients seemingly almost overlapping, or are they beginning to feel more seperate (from around 50ms onwards).
I'm not yet a full-on pro, still hope this is of more helpful to you than the answer LMQ gave you... Cheers!

@Max Lenz 🫵🏼👇🏼