Hazy IPA

Hi Gash - I recently came across a recipe ( all Grain ) for a Hazy IPA, and after the list of grains ( Grain bill ) it also requires 175 grams of Lactose in the recipe, however it does not say when to add this.  Should it be added in the mash , Boil, when ?  the hop additions are only after the boil, at 80Deg C  hopstand.  
Cheers