When I was dosing manually I always tried to leave at least a half hour between ca and alk doses. I don't dose magnesium every day but when I do I add it in the morning then my ca and alk at night. I also find it easier to premix a gallon worth of each solution so you don't have to bother with mixing each time. Check this link out for how to make homemade 2 part. I you let your calcium mix in before you dose your baking soda that should help with your milky water problem.
http://www.reefkeeping.com/issues/2006-02/rhf/index.php