It's not a date, it's a process. You don't decide once and then have to stick with that for time immemorial; instead, you change your plans as your goals and situations change.
Where you are sitting right now, is it worth busting it that much harder on your family's third job to retire 2 years earlier? You have a baby and a new job. Do you really, really want to spend every night and weekend working at yet another job to raise money that you don't actually need right now, just because in 8 years you might decide that you're done? Do you want to miss that time with your family? And how would your wife feel about you missing that time with your family and leaving all the parenting work to her?
And what are you planning to retire TO in 8-10 years? You know when that "I have to earn another $2500/mo" works? When you are excited by the opportunity to leave two years earlier, because you can't wait to get started on XYZ, and it's totally worth the extra work to get there faster. I don't hear that in you -- at all.
The point of FIRE is to balance your overall lifetime happiness -- basically, to give Future You a seat at the table, so Current You doesn't run around setting all his money on fire because fire is just so much fun. But that doesn't mean that Future You trumps Current You. There's no point in being miserable for 8 years just to retire 2 years earlier, if you have another option to enjoy your life for the 10 years you'd need to work.
Finally, consider that you are more than capable of continuing to bring in income after you FIRE if you want or need to. Even if you quit the day job and your wife quits her job, if you just manage a few cases and clear, say, $10-15K/yr, that decreases the 'stache you need by a LOT. It doesn't have to be all or nothing.
Tl;dr: Make the best decision you can now, weighing the lifestyle you want now against your future goals. Then look at it again next year, and the year after that, and any time something changes and you're not sure you're on the right track any more. Adjust as needed. Repeat.
FWIW, our FIRE date is based on when our youngest goes to college. We could FIRE now. But DH loves his job, and neither one of us will be in a position to earn anything near our current pay if we quit and find we need to work again. But really, the big driver is that we want to travel -- and not the "grab a week or two and throw the kids on a plane to go see cool old towns and speak a different language" travel. We want to stay in places for weeks or months at a time, and we can't do that with kids at home. Well, we could if we wanted to homeschool, but that's NOT the thing for either of us, and frankly, DS is going to have some great opportunities at the local HS that he wouldn't have with us (he is very into robotics and engineering and such; the HS has classes and teams and such, whereas that's not the kind of stuff we could tote around). Yadda yadda -- there were of course a million things large and small that played into our analysis. But the sum total of them all was that it makes sense to keep working until he's out of the house. And I'm ok with that -- I was the one pushing us to FIRE a couple of years ago, but I compromised on that, and DH compromised by agreeing I could go part-time in the interim, and so far we're both happy with that decision. But: if at some point that is no longer true, we'll revisit the decision and make a different one.