How Did This Come About So Quickly?!?!?

So about two days ago when Madison was getting out of the bath tub, she informed us that she had to do "poopie" and then a few minutes later she was going in her bath towel! So she was sure right about needing to go. Ever since that day she has been informing us of needing to go to the bathroom and then she walks to the toilet and tries to open it up. So today I figured I should get her a little potty if she is showing all this interest in the toilet and going to the bathroom out of no where. I went and bought her a potty today, and as we were walking back into the house from the store she says, "Poopie diaper". So I ask if she needs to go and she says yes. I ask if she would like to try to go on her new potty and she says yes. So we take the potty out of the box, set it up on the bathroom floor, put my little girl on it, and she instantly pooped in it!
WHAT?! She's only 18 months old! I did not see this coming and am not prepared for this! I have no idea how to potty train a little person! (Luckily for me Madison seems to know!) I didn't expect to be doing it this early. So while I go read some books and figure out what the heck to do, here is the most decent and appropriate picture I had of our new experience:

Here is her brand new potty we bought today. We even put her name on it:

And here's our girl on her potty for the first time. (and seconds later she actually "used" the potty if you know what I mean. Luckily for you I didn't take a picture of that. :-) )