Hi there!
I too had to go through a miscarriage and I understand how cautious it can make you when you become pregnant again.
As you can see from the many answers, it's a very personal choice. I, too, wanted to be careful at first. Then I realized two things. Baby stuff is expensive!

Planning in advance, getting info from friends and in stores helped us figure out what models we wanted to buy and so on. It made it easier for both our families to figure out who would buy us what. And it also made it easier for us to spread the expenses over several months instead of having to buy everything at once. For example, it's a good thing to shop for your stroller and car seats in advance so you can figure out what you want. But it's better to buy it at the last minute because that way the warranties will last longer after you start using it. Now that we've got all the big items planned (not all bought, but planned), my mind is more at ease.
The second thing I realized was while reading a book I fell in love with, Secrets of a Baby Whisperer. In that book, the nurse advises us to have everything ready by the end of the second trimester. That way, even if the baby comes early or if you have to be put on bedrest, you have chosen the items that YOU want and you don't have to ask other people to choose or buy them for you. I couldn't imagine someone else picking baby stuff for me or installing it all while I had to lay in bed or worse, doing it in a complete rush during the short days of my delivery hospitalization, so it made a lot of sense to me. But again, it's a personal choice.
And of course, one last thing that I take into consideration is... Holidays and Boxing Days speciaaaaals! We bought the crib earlier this month and saved over a hundred bucks because it was on sale until Dec 15th. We had a really good deal. You can be sure I'll go to warehouse sales between the 26th and the 31st to buy baby clothes and fabrics for my little boy.
Whatever you choose, just follow your instinct because the person who knows what's best for you and your angels is YOU!
Sophie