[Anton Kosarchyn]

Thanks for the reply! Your solution works great but I expanded it a bit with switch conditions, so now you can pass up to 3 properties (speed, velocity, value). So the extended code are below if anyone needs it:)
Thanks again!)

/*
Function can obtain time when some action happens (eg time when object speed was 0 etc.) It's based on algorithm of Dan Ebberts expression. You can pass 4 arguments:

1. property - eg layer.transform.position etc;

2. method - string value. eg 'speed', 'velocity', 'value'. Buy default function will obtain 'value';

3. axis of property - you can pass 0(x-axis) or 1(y-axis) for methods 'velocity' and 'value'. For the 'speed' method it doesn't matter, but you still should pass something(0 or 1)or function will return error;

4. triggerValue - numeric value, which triggers the function.

For example, you want someLayer to fade out in half of a second when layer's position will be 600px at y-axis:
eventT = eventTime (thisComp.layer("someLayer").position, 'value', 1, 600);
thisComp.layer("someLayer").opacity = easeOut(time,eventT,eventT+0.5,100,0);
*/

function eventTime (property, method, axis, triggerValue){
switch(method){
case "speed":
method = "speedAtTime";
var isSpeed = true;
break;
case "velocity":
method = "velocityAtTime";
var isSpeed = false;
break;
default:
method = "valueAtTime";
var isSpeed = false;
break;
};
var frame = timeToFrames(time);
var controller = true;
while (controller){
var t = framesToTime(frame);
var s = !isSpeed ? Math.floor(property[method](t)[axis]) : Math.floor(property[method](t));
var prevs = !isSpeed ? Math.floor(property[method](framesToTime(frame-1))[axis]) : Math.floor(property[method](framesToTime(frame-1)));
if(frame==0){
break;
};
if(prevs!=s){
if(s==triggerValue){
controller=false;
};
};
--frame;
};
if(!controller){
t;
}else{
t=0;
};
return t;
};