I'll share my experience just FYI - everyone is different. I had a long maternity leave (1 yr) but ended up starting to work from home at about 9 months; before that I worked on a book (but not for pay).
When my son was a true newborn I didn't get a lot done 'cause of the whole sleep issue but once I learned to nurse at the keyboard, I could do a bit. My concentration was off though.
Probably 3-6 months it was possible to get work done, before he was really mobile; it was in very short spurts. I still at that point didn't have a lot of energy to work at night and my husband and I hadn't worked out good sharing of care yet.
Starting when he was crawling I found it harder to balance. Mostly because he was a climber and way better at getting into things than we had thought with our babyproofing. (At 10 months he was not walking, but had figured out to push toys in front of things to climb them - go figure.) I also had mastitis though.
At that point my husband started doing more care and I was able to work 5 hrs on the weekend days and some at night.
Starting at a year, I WAHMd 20-ish hours a week, about 2-3 on the phone doing interviews, which had to be during naptime.
I found it really stressful myself. I felt like I was never giving anything my full attention. I got very tense about naps, because I had to book interview times with people, and then if my son didn't fall asleep I would be trying to deal with sounding professional with a shrieking baby. And my tension about it didn't help him sleep! And then he and I were at odds.
Also it seemed like that darn laptop was everywhere, all the time.
It definitely was possible to get the rest of the work done on the weekend and at night (although my son was not a great sleeper or napper, which complicated things), but the cost
was that I felt like I had very little "family time" (everyone all together) and that I was always, always juggling between parenting, chores, and work. It was "can you take him for two hours so I can work and after that we'll clean the floor and..."
Also he was walking and climbing a lot; he was not a sit and play kind of kid, even with playdough, rice bin, etc. And for me, work requires concentration. The best times were laptop at the sandbox, until I got sand in the keys.
This was, other than times we've been sick, the worst period of time for me.
Then I got a nanny for ten hours a week (half the time I was working) and that worked well, but it was not a lot of money coming in and I was not progressing much in my career, just treading water. (Still making contacts and stuff though.) Because I was partly contract, partly freelancing, I would get 40 hrs of work in a week sometimes and then have to stay up late and get sick.
Anyways, I fell into a dream FT job and decided to put my son in daycare. He's an extrovert who also has sensitive hearing so it took a while to find the right one, but we've been happy with the warm and caring environment. To be honest, it was also good for me to learn that other people will care for him. I am his best mom forever, but not his only caregiver and it's been a gift in that way.
I personally find it less stressful to have work at work and home at home, and I feel like I'm a better parent actually than I was WAHM. It is fewer hours at home together than I would like (working 30 would be perfect for me) but I can really relax and enjoy parenting when I am home. That's "home space" and work is elsewhere.
Everyone is different but I wanted to share my experience.