You may undertake simple checks at the time of your refill receipt :- LPG cylinders are subsidized and hence are delivered on first come first served basis. Hence you will not receive the cylinder out of turn. After your call matures, the supply will be made to you on next preferred day and time. For example if you are a preferred time customer, you will receive the cylinder next day on the preferred time slot after your call matures. For example if you are a 8AM to 11 AM preferred time customer and have booked your refill on Saturday 1st of June. But on that day distributor was delivering cylinders booked by customers on 25th day of May. After your call matures, say on Wednesday 5th June, you will receive the cylinder on same Wednesday between 8 AM and 11 PM. However if you are a preferred day and time customer of Monday and your booking matures on Wednesday 5th June, you will receive the cylinder only on 10th June, Monday.