Interesting... My experience has been the opposite, the first ~6 months they sleep so much that there is plenty of time to do things. Then you get a phase where they start to crawl and then walk around. In that phase, you have to be attentive all the time to ensure that they don't harm themselves or break stuff :). That really changed when our daughter was ~2, when she knew what she can and cannot do and they can basically play more by themselves. She is now ~3, sometimes she plays alone (she likes Duplo) and sometimes we play together. Since she usually goes to bed at 19:00 and is a good sleeper, we usually have a couple of hours every night for ourselves.

What I learned: your time does get reduced drastically, but you spend the remaining time with more focus/direction. Also, you use your time smarter. E.g., I used to do sports (indoor climbing), but now I just cycle every day from/to work (~1 hour) to stay fit. It takes approximately the same time as going by train or car.