hi Iggie, there is no major reason why, if the mirena is still in the correct position, that it cannot be taken out at any time. It is thought that it is easier to take it out during a period for some people, so maybe that's what they were thinking about - but to be honest, it can be taken out at any stage. i was not having a period - if one has been on mirena for a long time, then one often has no periods anyway lol. It took about 2 mins to get it out. The only time there could be a problem is if the mirena has shifted it's position - and a doctor should be able to see that when they examine you. So i wouldn't worry at all.
Just try to relax your muscles down there as much as you can when they remove the mirena, then go home afterwards, and lie down for a few hours - you will probably feel absolutely fine afterwards, and will want to jump for joy lol, but i suggest laying down when you get home, so that you continue to feel fine!!! - because the body has been traumatised having the mirena pulled out of it, and the uterus will be a little inflamed inside, so any rest that you can get will help your body recover better. Obviously don't strain yourself or lift anything or do major strenous excersise for a few days, just take things easy and you should heal up without any problems whatsoever. Removal itself is pretty quick and simple and pain free - just a slight discomfort if anything- not half as bad as having a pap smear test, which i always find terribly painful! And it is such a relief to get the damn thing out, it is like a black rain cloud being lifted from over your head! Good luck for thursday, look forward to a new better life from Friday onwards!!:)