next friday- 12 o'clock European time. For Estx50, Fdax and related options always the third friday of expiration month. Bund Future and Euribor have different expirations.
I make money trading estx50, but it took me 2 years to get there. Also trade NQ, but this works a bit different than NQ or ES. Be prepared, and most important don't trade the fdax until you are really good in estx50 over a longer time. Fdax is a really wild thing, if you can't ride it, you will probably fall. Anyway, good luck.