When we get ACK or NACK to inform transmitter, how much is the Latency?

Yes, correct.

I am using fixed PDSCH.
I am not using PDCCH.

Now, how should know the ack transmission time?
Shall we consider it as in LTE?
That’s the thing here, what I am trying to find out… :frowning:

The last field PDSCH-to-HARQ_feedback timing indicator.