Request for time during the stretch

[mick]

Adult OBR, R1

RH F1 in Set, took signal and brought hands together.
F1 is at full stop [slightly better than 2 full seconds, longer than normal] and looking at R1 over his shoulder. During the first second, I hear "something" (inaudible), then recognize BR requesting "Time"; a quick glance at the pitcher and he hasn't started his delivery [Hands still together and no foot motion].
I quickly call "Time! No Pitch" and step out.
I am a step-and-a-half out when F1 throws a ball in the strike zone.

F1 expressed his concern of my "No Pitch".

Usually a batter will be very distinct in his request and life is easier.

I heard, but did not recognize the request until almost two seconds after the initial *sound*.

Question: At what point should I ignore the request?

Thanks,
mick