Periods and IUD

I had my copper IUD fitted about 3 weeks ago and it was the worst experience ever 😫, in terms of the pain, the doctor and nurse however were so reassuring and caring which did help.

About 2-3 days after I had a heavy period as I was on my pill for 3 days before I had the IUD fitted.

Are periods usually late or do they tend to come early. Only just changed after being on pill for years and I’m bracing myself for them to be heavier and more painful but are they usually late at the start or is just at the start when your body is getting used to it or not??