Not sure why or how this is done, but I have seen many applications being processed out of turn. If you note the USANI number, then you will also find that these are much newer applications than your own which probably has been waiting at the consulate just to be acknowledged. My application has USANI34xxxxx which I mailed the same day on which I registered online, but I am still waiting for the OCI to be printed. Typically this out of turn processing is done towards the end their workday for processing the applications (by lunch time?) and will show the date of the following day for us (already next day in India).
It is also appears that there is no systematic way to acknowledge and process the applications in the order in which they are received.
It is also appears that there is no systematic way to acknowledge and process the applications in the order in which they are received.