Time becomes a luxury once you become a parent and when you have a couple of little beings who depend on you 24/7. Sometimes it's not about the pockets of time available in between family, work, and life, but the actual mind-space available to day dream and just be. Have a read at this article from The Atlantic, it refers to kids, but very much applicable to adults too.
Last year, EB and I decided that we'll each take time out (separately) to go on a solo holiday each year, relieved from all parental duties for a couple of days. Kind of like an 'annual leave' for parents as aptly put by one of my friends. Where time and resources allow, this has been largely beneficial. 4-5 days seems to be the optimal time for a quick break, long enough to disconnect and reconnect, yet short enough to not let too much guilt seep in.
But even more important (and realistic) is to figure out how to carve time out on a daily basis for self-care. I have an ideal routine of morning meditation/yoga and writing in my journal, but that falls through half the time. It's hard to make it work, but it shouldn't be. Other little things such as making a cup of tea, losing yourself in a good book, watching the clouds, going for a run, enjoying the breeze on a bike ride, and strangely, a rather frivolous activity such as spending time to properly moisturise do wonder.
I love this quote "You can't pour from an empty cup" - there's much truth to it and serves as a good reminder. Read more about parenting and self-care here if you're interested.