Thanks and in real life too

I got my game today and what I expected to happen from the demo until I bought the game is that they all had died. But I started over using the Monks guide and I feel comfortable leaving them alone tonight. I've been running it at 2X but will change that before I turn off the computer tonight. I have one villager who's is the only farmer I have and she works all the time either farming or researching on her own ( she was a gather, then researcher and now a farmer). My question: can she work too much? there's only one other villager who works almost as much as she and he's a builder. I don't want her to have any children yet. But I do have a new 2 year old and the first child is almost old enough to train. I'm thinking of training her to be a farmer and give my first farmer a rest and have a baby, if that's a rest I feel secure that they won't go hungry. How much further in the game should I be before I have another baby??

Thanks.