Hopefully you are bottle feeding if you are doing the Master-Cleanse with a new baby. Otherwise all the toxins you release will go through your breast milk to the baby. So do not do the Master-Cleanse if you are nursing!
It is very important that the SWF (Salt-Water-Flush) be done in the a.m. so your stomach is completely empty of everything, even water. The proportion of h2o to salt is essential so it runs through your body without being absorbed. Hopefully you have read the book, if not it is available to read online. Good luck!