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So, it looks like you got it right first time! Possibly a little bit too far back, but as I haven't got a dew strap, I'll leave others to make more specific advice.

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Looks OK to me. If you fit a flexi type dew cap that will fit over the "black bit" at the tube end so you have two choices: place the heater strap behind the dew cap as in the top photo, or wrap the dew cap round the heater strap. Experience indicates that the latter method is a bit unstable even though it gets more heat where it's wanted (into the corrector plate). With a larger scope this may be an issue, on my C11 I solved it by using electrical tape to hold the heater strap firmly in place allowing the dew cap to be fitted reasonably firmly. With a 6" scope I don't think there will be an issue, even the central bit of the corrector plate is fairly close to the heater strap even if the heater strap isn't in the optimal position.

If you're using a "screw in" type rigid dew cap, or no dew cap at all, the issue is moot, fit the heater strap centrally over the black metal corrector cell mount.

In use, the heater strap power setting should be adjusted so that it's at a minimum consistent with keeping the corrector plate clear. A good way of judging this is by dew forming on the outside of the tube; the setting is about right when dew is forming except within a couple of inches of the heater strap. Too little heat = misted corrector (very bad), too much = tube currents (bad but, unless imaging planets at high magnification, not insufferably so). On balance, better to err on the side of a bit too much as it's a lot easier to prevent dew from forming than too evaporate it once formed.

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