synchronize two counter outputs on 6071E card

Well, it's the usual how do I synchronize two counters problem.

I'm using the 6071E with DAQmx .NET 4.0. I define a Task and attach to it two counter output channels with implicit timing and zero initial delay . When running the program

I catch the first edge with a scope single trigger. There is always a delay between the first edge of ctr0 and the first edge of ctr1 of 16.3 microsecs. Is there a way, besides setting the initial delay of ctr0 to 16.3 microsecs, to make the counters to always start together? what is the source of the delay(software/hardware) and should it always stay constant.

any help is welcome