There's 2 places to claim for VAT; before and after checking in.
For luggage, you can claim for VAT before checking in. However, the risk is that the queue might be very long and you will have to arrive way earlier prior to check in.
Alternatively, if your luggage is small enough to be a carry on, you can claim for VAT after checking in. Queue is shorter but similarly the counter is also lesser.
There is a 2 step process. A stamp have to be obtained before getting the refund from another counter.