I have assisted in whelping several litters of pups through out the years including my own as well a few litters of kitten from time to time. I am in no way an expert but I have done intense research in great detail in order to prepare myself for breeding / whelping my own Yorkies.
You need to start feeding her puppy food if you havn't already. Than start getting your supplies ready now so that you are totally prepared for any surprises that may occur durring whelping.
Pease feel free to contact me if you have any more question I will be more than happy to help in any way that I can.
Here are some informational sites that will help you prepare for her pregnancy & whelping. You may also want to look up some videos on utube or some other site so that will you are prepared and know what to expect during her delivery.
http://www.debbiejensen.com/heat_cycle.html http://www.ehow.com/how_2261_deliver-puppies.html http://www.ehow.com/how_7739802_ready-dog-having-puppies.html