Personally, I like to study in the morning, so I usually hole up somewhere in my house where people can't bug me. 7am to 10am was my designed GMAT time. Since I used the same time every day, eventually my family learned not to bug me.

Many of my private students have a hard time transitioning from the home-study environment to the test center on test day. In those cases, I typically advise people to start taking practice tests in an unfamiliar environment. I.e. wherever you do most of your studying, you should be taking your tests somewhere else. Preferably some place distracting that will help simulate the stressful conditions of the real exam.