I had mine on 25/11... we weren't keen on having it done in the first place, but after I'd suffered pretty badly with just a cold, we were a bit weary of what would happen if I did catch anything worse - and given that I work in a school, and there are plenty of germs around, we decided to go for it.
It didn't hurt at the time (and I am pathetic with injections of any kind) and I felt absolutely fine that evening. The next day around lunch time I started to feel a bit 'dozy' which is the only way I can only describe it, and by evening, my arm was killing me and I was also generally achy.
I couldn't sleep on my left side for 2 nights and my arm is bruised, red, hot and sore (pic kind of shows it). Good news though, is that baby is absolutely fine.... no decrease in movement and I've listened on the doppler (which I hadn't done for weeks) and she's fine.
I'm sure that you and your baby will be fine too... just don't expect to be raising your arm for a couple of days after!