If you are using a cooler MLT, don't forget to preheat your mash tun. Put your strike water in there several degrees hotter than the actual strike temp you are planning for. E.g. if your strike water is supposed to be 160F when you mash in, put it in there when it's 170F and let the cooler take that excess heat out. Then when you stir in the grains, do THAT at a degree or two higher than the intended strike temp as well. It is easy to drop your mash temp a degree or two in a cooler, but much harder to raise it a degree or two.
With all that said, I recommend against being way over your intended mash temps if you can avoid it. Once you start getting into the upper 150's / lower 160's your mash converts very quickly, so you want to try and dial it in within a couple of degrees if you can.