Since you aren't able to find the topic, I'll try to explain it to you. It is impossible to keep your IFR while flying with ATC instructions. Let's say you want FL410 as your final level. File and save it for FL 410. In ATC clearance you'll be instructed to to climb FL410, but don't worry about that first. Well follow instructions till you want to take-off and when airborne ATC will hand you off to another center/departure. Acknowledge, but don't call on the next center. Just continue flying. Contact them before descent, by then, you should be at FL 410.