I'd do it early, I get a few people call me as soon as they are pregnant, and some around 13 weeks. Of course you get those last minute ones too who have a last minute freak out LOL but earlier is better as Doulas need to plan everything 9 months ahead of time Plus more time to get to know your doula. Most doulas only do 1-2 births a month due to family commitments so they can book up quick.