When do you hire a Doula?

If all goes well, this will be our first child. My first pregnancy ended in MC around 5/6wks, so I had barely started to consider all my options. This is our rainbow baby and one thing I have decided is that I would like to get a Doula, so I’m wondering how far along before I should start activity contacting local Doulas? I’m currently 4wks2days.