Most importantly, warm the car up to normal operating temperature before driving it hard. The owner's manual says drive it for 5 minutes before revving above 4,200 RPM.
I'd say run it until the temperature gauge has risen to normal operating range and become stable, then have no fear of taking it to 6,000+ and occasionally to the limiter. The engine computer (DME) is designed to prevent the engine from being revved above it's safe range during upshifts and the Tiptronic transmissions will not permit the engine to be put in a condition that will allow an overspeed even in downshifting. The only way that you can exceed the safe operating RPM is to downshift a manual transmission while you are near the maximum range.