When should my period come ?

Trying not to over think this because I know Skyla and IUD’s in general can mess with your period cycles. I started my last period on Dec 2 and got my IUD inserted Dec 5, I bled a lot longer (12 days) instead of my usual five.. before this I was in the Nuva ring and my periods were pretty on time but super heavy. When should I expect my first period on the Skyla ? Is it ok that it’s late ?? I read that I might be pregnant if I haven’t gotten a period after 6 weeks on the website