One important thing to remember about building up a stock of milk for returning to work is that it tends to be difficult to collect much milk while you are breastfeeding as well. So if you only get a small amount don't worry this is normal. You can add all the small amounts you manage to collect together until you have the amount you want. Once you return to work you will be expressing the milk instead of feeding the baby and so collecting the milk will be much easier.
It is often suggested to store the milk in small quantities rather than large ones. This way if your baby doesn't want much milk you don't waste it as once the milk has been given to the baby you need to throw away any that she doesn't drink. One suggestion to keep milk frozen in small quantities is to freeze it in ice cube trays and then store the small frozen cubes of ice in freezer bags. Remember to date the bags correctly.
Human milk will keep for up to seven days in the fridge, however, and fresh milk is much easier to manage than frozen milk. So I would consider a plan where you collect the milk one day to feed to the baby the next and try to avoid freezing the milk if possible.
As for the best time to pump your milk - the best time is when you find it easiest. Many mothers find that first thing in the morning is the easiest time. They feel full and the baby often only wants one side so you can pump the other. As someone else suggested pumping one side while the baby drinks the other side helps with the let down but can be difficult to manage unless you are an Indian goddess with multiple pairs of arms.
Although your baby drinks many times in the morning at the moment she is likely to drink more from the bottle and thus last longer between feeds. Babies tend to over eat when drinking from bottles, even when it is breast milk in the bottle.
La Leche League in Hong Kong has a special forum for working mothers who return to work. You may be able to find more tips about pumping from these mothers,
http://www.lllhk.org/Englishindex.html
Best wishes,
SARAH
Sarah Hung IBCLC
www.lotuslactation.com