How to control internal ADC/DAC buffer in AD9361

Hi

I assume there's a circular buffer inside ad9361 chip before ADC/DAC converter and depending on power up time they could have any random position before we drive actual data to DAC or ADC. This is a problem for my application where I need to know a deterministic delay between transmit DAC on one AD9361 and ADC on another ad9361 .

To clarify my problem I set an example. Suppose I have 2 ad9361s, one is Tx and one is Rx. At time T0 I turn on ad9361_1 and some time later at T1 I turn on ad9361_2. Yet I have not sent any data, so I assume DAC buffer is circulating around and sending out noise. I suppose buffer size is 256 symbols. Imagine at T2 I start to drive ad9361 DAC and at this time buffer is at location 32. my first data sits at location 0 of the buffer so it needs to circle 256-32 to reach to my first data to send. So technically I now have delay of 224 on my DAC side and the same scenario could happen at ad9361_2 where the ADC buffer is circulating before it could receive the first data. 

With this example I hope I conveyed that we could have a deterministic delay between 2 operating ADC/DAC. Now I wonder if I could remove this deterministic delay by maybe resetting DAC/ADC buffers? or any other solutions. Or maybe there's no such buffer before or after ADC/DAC in 9361? 

Please let me know your thoughts and let me know if you have any questions.

Thanks,

Sean