About [TIMING] start frame and end frame influence

[illuminix]

Why don't you use "time test" operator, set to frame (for example 50), and then in new event you place cluster force. 
That way, in 50 frame, a force will affect every particle.

yep, that was another method i was considering.  but i thought TIMING panel was interesting, as it enabled me to keep everything in a single event.

not sure if having things in a single EVENT is better or worse, but this was a function i didn't see in particle flow for example, so thought i test it out.

or alternatively, i could keyframe the FORCE INTENSITY, but i liked they way how i could setup the FORCE, but control when it is ACTIVATED via the TIMING section.