Re: beginning to pump
Print out some information on paced bottle feeding (http://kellymom.com/bf/pumpingmoms/f...ottle-feeding/) and discuss paced feeding with the babysitter.
Send lots of small bottles (think a mix of 1-3 oz portions) rather than a few large ones (this reduces overfeeding and forces the caregiver to pause the feeding even if she wasn't going to).
Stick to the standard of sending about 1.5 oz of milk per hour of separation. 18-20 oz is on the high side, unless you intend to be gone for about 12-13 hours. It's fine to send some extra milk- some days your child will probably eat more than the 1.5 oz/hour standard, particularly during growth spurts. But IMO you want to start the caregiver out with a more typical amount and send the extra frozen, so that it takes effort to go get more.
Babies often resist taking bottles from mom. Why would they want a silicone nipple when they know mom has the real thing just millimeters away, right? So it may help to have dad or some other caregiver offer that first bottle.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"