first of all, you need to check the auto upgradation checkbox while booking.. only then your PNR will be considered for auto upgradation.. auto upgradation rarely happens and that too with mostly single passenger PNRs.... You must check your PNR after chart preparation... Even if you don't check, the TTE will let you know... but you may have to contend or even fight with other passenger who might have occupied your original seat till the TTE arrives because you don't know that you have been upgraded... ! Once I was upgraded from 3A to 2A. I had not known it beforehand but I got to know from the TTE before anyone came to my original seat... !