As soon as you throw in a couple hunks of cold meat the temps will drop. Another thing to do is to open the vents as wide as they will go, and that may help to drop the temp. My GOSM has two vents on the sides near the bottom, and one on the top. I find that I need to open them late in the smoke when the meat has come up in temperature.
Hope this helps.
Take care, have fun, and do good!