Basis for processing itr at cpc

Friends/Seniors

Are you aware what is the criteria or basis on which a return is taken up for processing for generation of intimation under section 143(1) at CPC. Is it date of uploading or according to first alphabet of assessee or turnover etc. I uploaded ITR4 for my father on 28072014 having refund due and it was processed recently. I uploaded my wife's ITR4 on 17062014 and she is yet to receive the intimation as it has not yet been processed.

Please share your thoughts.

Regards,