That's really hard to answer, as it is different for everyone. It is apparently supposed to hurt a little, the doctor advised me to take pain killers (panadol) before coming in. I forgot to take them but luckily I didn't feel any pain at all. The doc said I was the "perfect patient", LOL, as I didn't flinch at all and didn't even have any spotting.
A little pain and spotting for a few days after is very normal though. thinking back (I had mine put in a year ago) I think I did get a little period-like cramping for a couple hours afterwards, but it wasn't too bad
Take a panty liner with you in case of spotting/bleeding afterwards.