I was 30 when I got married so I didn't really have a lot of time to waste when it came to having kids since I wanted more than one. But getting married later, that also meant we were a little better off financially since we had slightly higher salaries and already had some savings and retirement established so we didn't spend much time trying to build more savings.
When we started TTC, I had enough sick leave to cover my full 12 weeks FMLA and enough in the bank to cover me for an additional three months. I wanted to stay home as long as possible.
As fate would have it, we were unable to conceive on our own and ended up having to burn through some of our savings to pay for IVF. Fortunately, I had excellent insurance that covered a significant portion of the treatments but it made a big enough dent in our savings that I changed my plans for staying home. Best laid plans...
My children are 3 and 4 and we don't make enough to really even cover our daycare costs. Payraises have been non-existant and rising insurance costs have slowly eaten away at our take home pay. For awhile we were making less per month than we were when we first got married. But there's light at the end of the tunnel as daycare costs will end soon as well as a few other recurring expenses.
All that to say...you just don't know what life's going to throw your way. Plan as best you can but don't get too hung up in those preparations. Give yourself a nice savings cushion and then have at it.