Hitting first crack at 6 or 7 minutes is not bad with this method if you can keep control and not hit your desired endpoint for at least another two minutes (and continue a slow rise without stalling or wobbling). The bottom heat shuts off somewhere between 335 and 355 depending on your exact stir crazy, so the only real effect is to drive the temperature up in the early part of the roast. If you are roasting at least 8oz, it will help stabilize the temp and drive off the moisture. The actual temp on the CO unit is never anything like the dial says, it has more to do with the ratio of time on to off. I've found that I get the best environmental temperature ramp by starting out at a 400 target then dropping to 370 after 4 minutes or so on an unmodified halogen element oven. You can easily hit 440 bean temp at that setting (!) with this configuration, but most importantly you will get a proper ramp arc without a rate of rise increase after FC starts, and you will not stall the roast. This sounds completely opposed to what many sources recommend, but it will give you the best development for a 10-12 oz roast. This has been my experience with at least 15 ovens, some of them split wired, over the last 9 years. I have roasted at least 2500# by SC/TO, and rarely monitor temperature any more, I can tell by the smell... Nowadays I mostly use turbocrazy for sample roasts, as all my production is done with a 5# old school RK and a 14# homemade drum, but it is still my 'go to' method for small or precious runs. Every oven has its own 'personality', the halogen element Sharper Image device is my preferred one these days, with the old Galloping Gourmet the runner up (but these usually have to be run hotter).
