How long before you can get pregnant after IUD removal

Khadija • I like to think I`m cool. Happy and Silly mama of 2!!. Engaged to a strikingly persistent man.
My finance and I are trying to have another child so I took my IUD out ( I had the Mirena). But I wanted to know about how long it could take before I can get pregnant. I didn't expect it to be able to work immediately. I bled twice and had sex in the 2 day period in between blood boughts. I really want to have an idea of if (or when) I should be worried../.