Hi Junebug
As the others have said, the needle itself is REALLY surprisingly easy - i barely felt mine at all. It's not painful, but it felt a little ticklish/awkward lying on the table whilst the doctor feels around for the little ball under the skin.
Advice:
don't worry...seriously the needle is nothing!
take a pillow so you can place it over your stomach on the ride home, as the seatbelt might irritate
do not try to eat or drink anything for a while (ask your doc). Take everything nice and slow. I foolishly tried a SINGLE SMALL SIP of Water 1 hour after my first fill, and almost vomited it everywhere 5 minutes later.
pause for a little while between swallows as your gut is slower than your brain and 2 swallows too quick in sucession can get you!
IF when you do eat too much/too fast, take a break, give it 2 minutes to hopefully work itself out. if the feeling doesn't go away i find it helpful to take a few sips of water - it WILL make you feel really crappy, but it has the effect of either making you gently vomit up the blockage or letting it slip through the band peacefully. This is a last resort though to resolve the problem once it has occurred, you must not get into a habit of drinking whilst eating or the band will be useless
Good luck tomorrow