hi friend get the pup used to the whistle from day one (this is for spaniels it might be different for labs or hpr,s) one short pip stop and sit do this every time you have him on the lead walking , eventually he will associate the two pip and sit, but hes only a pup so don't be in a hurry ,
two pips you use this to turn the dog ,
four pips recall , use it every time you feed him , or praise him he,ll soon put the two together whistle means good , like any training you get good days and bad days good luck .