I think the problem with academia is that a lot of the work is not completely finite: you can always be doing more or better. People will have their own definitions of what it means to be successful, and also of what it means to be a good parent.
For me, as with other PPs, a mixture of judgement and plain good luck have allowed me to reach and sustain the level of success I want. Fundamentally, though, I think the thing that most helped me was that I waited until I was already quite successful before having a child, which I realise is no help to the OP.
DP and I agreed that we would go all out for our careers early on (we are both academics) and would only consider a child when we had reached a level where we perceived our reputation and status would allow us some degree of flexibility and protect us from the worst of what we had seen with other, mostly female, academics whose careers were completely derailed by having children when they were post docs or lecurers. It sounds very instrumental, but we sat down with our CVs and said 'we are both Readers now. If we had to really step back for 1, 2, 3 years, where would that leave us against the criteria for becoming a Professor?' And it was very much 'us'. There was no question that this was not going to be a 50/50 thing. It helped that we were both fairly ambivalent about having children and were ok with the idea that it could be harder, or even impossible, to conceive if I was older. Through a lot of planning and some very fortuitous timing, we were both promoted to Professor when DD was a toddler.
It has really helped that we are both academics, so we both have some degree of flexibility, but also we do a lot of picking up the slack for each other in the evenings and at weekends, knowing that at other times the situations will be reversed. We were lucky that DD was an easy baby, we had an excellent, late opening nursery just a few doors from our house and DD's school is at the end of our road and has an after school scheme. We could afford to buy a family house 10 minutes from work so we don't have to factor in hours of commuting. Together these things mean that as long as I focus, I am not working significantly less hours than I did before DD was born.
Like geekaMaxima, I was also really lucky with research grants. I applied for a big grant when I was on maternity leave and getting that and then two others have meant that I have not had any time without research buyout since DD was born nine years ago. Currently, I also have admin buy out and have chosen my admin roles carefully, avoiding as much as possible the ones that are too unpredictable or time-consuming (which I did do earlier). The only u/g teaching I currently do is on a course I designed, which is completely in my area and which I could be 'good enough' at teaching with almost no effort if that is what I chose. This means if I want to I can work from home with no interruptions a lot of the time. It is very unlikely I would have been able (or felt able) to do this if I had had DD earlier in my career.
It isn't easy, and there have certainly been times when I have felt I haven't been spending enough time with DD, but as time has gone on, I have seen that it balances out. I wouldn't have another child though. While it is not unusual amongst senior people in my department to have two children (but not more), while we make it work with one, I don't think we could with more than one.