as a normal informal practice by some commuters , board the train in some other reserved compartment and slowly move to ur compartment , by which the train reaches TBM and then show the tkt to TTE that time . or keep ur luggages on ur seat and do doorstep fanning till TBM and show tkt that time . sometimes some tte may permit and some maynot . but they will mark ur tkt only after TBM only...