in the case of dogs,if we consider,discharge is a sign that she is being ready. milk doesnt come before birthing. sometimes the harmones produced during the labour are needed to make it come in.
Many females it only takes about one week before here do date. So you want to get here bed ready for birth because its going to be soon before she gives birth. Try to keep here at normal temperature because they change keep them in 99. 5 when she is going to give birth.