Any changes you make to your W-4 now will have limited effect because it is close to the end of the year, but you probably want more withheld than less, to avoid the possibility of a penalty.
I recommend the IRS calculator here.
https://www.irs.gov/individuals/tax-withholding-estimator
It may be harder to use with the new job, because it works best if you have at least one paycheck. But you may be able to estimate. I would also use the calculator again in January, after you both have your first 2025 paychecks, so you can reset your withholding for the rest of the year if needed.
If you don;t want to use the calculator, you can start with "withhold at higher single rate" and make sure the children are only listed on one W-4, not both, so the effect of the child tax credit is not counted twice.
The phase-out for the child tax credit starts at $400,000 income for married filing jointly.
