I think with the various answers that it depends on the examiner. When I took my private back in 1992, I had to bring the cross country plan with me to the oral exam already done (he had given me the routing). After the oral was done we departed on the flight and the first thing we did was begin flying the cross country I had planned. As soon as I could calculate in the air using an E6B (not the electronic type...the whiz wheel) our ground speed and fuel to the first waypoint on my flight plan, then we could go on to doing the other parts of the private check ride (stalls, steep turns, landings, etc....)