Gah, its the worst to do an audition or performance while jet-lagged. It's best to avoid it all together, but here are some ways I've learned to deal.

1. Do your normal routine no matter where you are - yoga, stretching, amount of time to warm up. If you skip steps, your body will be like “what the heck?”
2. Sleep is huge when your jet lagged. If you have trouble sleeping like me, you need at least two nights good sleep to feel normal. Unisom, theamine, and valerian root work as sleep aids for me. It’s my mind that keeps me awake. 
3. Focus your mind on the task at hand, not your life at home. That will help you adjust to being in a different time zone. 
4. Water water tea water water tea water. FYI It’s okay to drink Berlin tap water, even though people still drink bottled. Don’t over caffeinate, I did that before my Düsseldorf audition because I wanted to sit in the dining car and read- I think I had 3 cappuccinos. Not good, made me feel jittery and ungrounded.