1. Make your purchase, and ask for a photocopy of your reciept.
2. Customs first to inspect and verify (stamp & signature) your forms.
3. Then check, or hand carry your new treasure(s) with you.
4. Then, with your supporting documents, proceed to the VAT refund desk.

TIME TIP:

If you are travelling elsewhere in Europe after Germany, and run out of time to process and collect your VAT refund, or the VAT desk is closed, you can also process that refund at other European airports in EU countries.

This happened to us once returning to Switzerland via Frankfurt. I made a purchase at LH Worldshop, but the VAT desk was closed. Home we went.

I had business two weeks later in Italy, and took a chance and processed the VAT refund successfully at Malpensa, while there, with a few other Italian leather products.

By the way, Switzerland 2, Ecuador 1 in Brasilia today.
HOPP SCHWIZZ !!!