DD is now almost 10 months old, and I didn't get seriously back into writing until she was about 7 months. I probably would have done it a lot sooner if there hadn't been so many other transitions and changes in my life -- getting married and moving across the Atlantic being the two big ones.
I write during nap time, which for me is a routine. DD unlatches, I put her down, then it usually takes me 15-45 minutes to get around to actual writing. That includes a short lie-down (5-20 minutes) making a fresh pot of tea, and getting my computer to the dining room table. Her naps last anywhere from 20 minutes to a bit over 2 hours, and sometimes I get up in the middle to nurse her back to sleep. Sometimes, like today, that means I'm just about to get going when she wakes up again.
It works pretty well, for now. I occasionally try to write at night, but I've never been a night person and my brain works best in daylight hours, so I'm trying to spend a bit of time in the evenings reading -- reading actual books, that is, not the internet. Before DD was born, when i was living in Boston, I would go to a cafe and drink chai for an hour or two every day, usually in the morning but sometimes in the early afternoon, too. That was great. I really miss that cafe, and the chai.