Since grain is room temperature, you need to heat your strike water to a higher temperature than the 152 degree mash temperature target.
For my system, I do 1 quart of water per pound of grain. With those ratios of water to grain, I heat the strike water to 16 degrees above the target temperature, or 168 degrees.
When I add the room temperature grain, it absorbs some of the excess heat and the mash temp settles in very close to 152 degrees.
It the temp is too high, stir in a little cool water. If its too low, stir in a little 180 degree water and recheck the temp.
With experience, you will be able to hit the target temperature.
Even if you are a couple of degrees high or low, your mash will convert and you WILL make make sweet wort.