Before/no kids – joint account that you both pay into for household bills and other shared expenses worked fine for us. Bigger things like holidays we’d just both top it up for that month.
After kids, it made more sense to make the joint account the primary one, pay salary into there, effectively anything necessary for day-to-day stuff goes out of that, for us or kids. Set up a budget and syphon off a set amount into each of our personal accounts each month for “fun money”. It varies depending on how tight things are that particular month.
I can see the case for getting to the latter one sooner but until my wife was on maternity leave there didn’t seem like a pressing need to make the joint account the primary one. But then we didn’t feel the need to budget until then either, we were fortunate enough to both be earning decent money and not need to think about it too much. Plus we lived together for years before marrying, so it wasn’t like we were changing our lives that much in one go. In hindsight it would have made sense to do it earlier, it does make a lot of stuff much simpler.
YNAB have plenty of good stuff about combining finances. https://www.youneedabudget.com/learn/guide/join-forces