The Miscarriage Factor: When Is It Safe to Plan?

Here I sit, six-and-a-half weeks pregnant and I can't help but think: what if I have a miscarriage?
I researched miscarriage statistics and warning signs online - obsessed much? According to the March of Dimes, 50% of pregnancies result in miscarriage. As for recognized pregnancies, 15% result in miscarriage. More than 80% of miscarriages occur within the first three months of pregnancy. (All this according to webmd).
I began doing the math: I got pregnant after my first round of IUI, which carries a 20% chance of pregnancy, so what's the chance I'll have a miscarriage? Is miscarriage a greater risk for people who had IUI?
I want to jot down baby names, paint a nursery, buy onesies. I want to buy a copy of "Where The Wild Things Are," browse cribs, buy new clothing because I blew the button out on a pair of fat jeans. However, I wonder ... is it too soon?
Worrying over a miscarriage is pointless because it's going to happen whether I worry or not but when is it time to prepare for baby? Perhaps after the 20-month mark, just to be sure. Some say throw caution to the wind and prepare today because those nine months fly by!
Miscarriage, the elephant in the room, is on the minds of many expectant mothers, if not all, and I wonder how they deal. No one is perfect, we all have worries and fears, especially when it comes to mothering. Will I be a good mother? How fat am I going to get? Omg, I'm going to be a mom ... is it too late to run for the hills? How will I go without sleep? Will delivery be painful? What about the what-ifs -- i.e. miscarriage and birth defects?