I usually just try to guess about how much time I've got until the water hits 170°, when I'm about 30-40 minutes away from that, I have my steeping grains in.
Once I hit 170°, I take them out and I don't really mess with the burner. I just let it continue to build up to boiling. When I get to the point where I'm boiling, I start stirring like crazy to kill the boil and add the extract in slowly. It helps to have someone else pouring while you keep a little whirlpool going. I don't think I've had any scorching issues to date.
That being said, this is on my kitchen stove. I have a new propane burner that heats my brew up about 3-4 times faster, so I expect to have to change this method when I use it. I'm thinking I'll probably have to kill the flame when my grains go in or it will get to boiling in less than 30-40 minutes, fo sho.
*edit* I'll probably kill the burner when I add extract too. I think it all comes down to avoiding scorching & that's why they tell you to kill the heat.
I definitely don't do the whole take the pot completely off the burner thing either. F lifting all that.