make a new Null, attach all layers in your shot to the Null.
apply this expression to the Position parameter:
n = position.numKeys;
if (n > 0){
t = time – position.key(n).time;
if (t > 0){
freq =8;
amplitude = 10;
decay = 6.0;
s = amplitude*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t);
e = amplitude*Math.sin(freq*t*1*Math.PI)/Math.exp(decay*t)
value + [s,e]
}else{
value
}
}else{
value
}
then add a keyframe for position at the time you want your “impact”