You can recruit a bunch of them from the start. What you need to do, is to get them some practice before they get good enough at their jobs.The "problem" with the difficulty is that its curve starts off high. At the very beginning letting a single one of your girls get incapacitated for a day can effectively brick your playthrough. But once you get like 5 of them it becomes smooth sailing and only keeps getting easier and more monotonous.
In many ways, it's like an RPG, where you start as a commoner who can barely fight a rat, but a few levels in, you're a formidable warrior.