MP5, You could wait till you get back to start, but it won't kill you to take a week off. just train hard and eat right till about 4-5 days before you go and then work your ass off those days till you leave, since you have some rest time and the juice in your muscles will repair nicely. Rest for first three days of your trip and the last few do set of various push ups, find something to do some pull ups, a few things to curl, and most importantly keep up your diet and you will be ready to come back and hit the gym with 110%. Good luck with your decision bro!
Mass Monster