I think we are a bit unusual and it isn't perhaps what I'd recommend for other people, but we (accidentally) did kids then career and it actually worked out really well for us for various reasons. We accidentally fell pregnant early 20s, post Uni but start of careers. We were minimum wage pretty much, but that did mean we got nearly all our childcare paid for by tax credits. I worked part time and did the postgrad qualification I needed alongside that.
I was qualified and working full time when mine were 5 and 2, 5 years later I've moved up 2 levels and DH has also been promoted, we earn vastly more than we did back then, from below average to well above.
We were able to buy a house by the time youngest was 3 so childcare was less of a hindrance to mortgage. And by the time they were in school I was senior enough to have a much more flexible role able to leave early etc, that would have been harder in my junior roles but nursery provision was better than school so wasn't an issue.
I'm now applying for my next promotion, we live in a large home (owned with mortgage) holidays, outside school activities and lots of flexibility in our jobs. The toddler years were a bit of a balancing act and busy, but we are very comfortable now and do feel quietly smug that we are passed the difficult baby/toddler days, career kick off, trying to get on the ladder etc in one fell swoop and feel like we have lots ahead of us to look forward to, and only early 30s.
That said lots of potential pitfalls so as I say not sure id recommend it but very pleased with how it's turned out for us!