do u mean finish flowering so u can harvest...... or do u mean how long till the bottom of the plant gets buds on it like the top does? if u mean the 2nd 1 then it depends on the hight of the plant and the light u have. in sunlight it shud all bud at the same time but on a tall plant under low light the bottom will take ages and only have a few small buds.
i cant speak for standard growing, but in scrog all the buds from within a week of eachother. usually faster.