Hi Jerome,
The multiplexer(mux) on your card will sample all of the channels in order. That is, channel 0 will be sampled first, and the channel 1, and so on. What happens is the mux will then take all of those samples and send that information to the ADC. With Traditional DAQ, the convert of all channels will be done as quickly as possible between sample clocks.
I hope this helps. Have a Great Day!
George