I started right away with putting money into retirement accounts(partly due to this book: http://www.amazon.com/Automatic-Wealth-Grads-Anyone-Starting...).
While it hurts a bit each month to put money away, in the end I know it'll be good for "Future Me". I currently have 3 different ones: a Roth IRA (I used to put in $400/mo, but now only do $200/mo if I can...the next accounts are all automatic though and I don't skip those), the 2nd is a 403b (similar to a 401k, but available for people in the public sector) which I put $1000 into pre-tax, and the 3rd is my life insurance/savings account which I put $400 into each month (this is a bit extra on top of the regular premium so it'll build value as an additional income source I can tap into down the road). Both 1 and 3 are after taxes and #2 is my only pre-tax one. My savings account right now isn't too great partly because so much goes into the future retirement accounts, but I try and put another $300/mo into that if I can, but some months I end up tapping into that due to extra expenses that come up. (Sounds like maybe we should have a separate thread on how much people put away each month and their reasons for doing so :-).
I think some of the others are correct though, you can definitely start now in your free time with at least creating some accounts and started to do a little bit (the key thing would be being consistent with those actions...as an example, I've always been an HN consumer, but I hardly ever commented...now I'm making an effort to add my own thoughts to posts and share what I have to say because I'd like to build up my karma :-).
I agree with your comments though that it's hard to demonstrate your skills and capabilities to employers when all you have is your resume and not these ancillary profiles and public information spots that seem to be used a lot in determining whether someone's skills are adequate.
Since I work in a college IT department I feel like I'm automatically ruled out because of my background even though I always include a list of the various projects I've worked on over the past 6 years and the increasing levels of responsibility I've acquired.
The other negative I have is I'm probably my own worst critic and don't always see my own accomplishments in their best light (I'll think to myself, "Self, well you don't really have any Ruby on Rails experience so that automatically disqualifies you from all of these jobs, let's see what else is available...". That's kind of a self-imposed problem where I need to do a better job of selling myself.
Actually right now, even though I enjoy my job quite a bit, all I'd really want is the ability to tap into some of the knowledge of Silicon Valley to learn new things (by working part-time remotely and maybe sometimes in person with a company) that I just can't learn here so I can bring those into my current job and apply them, but there don't seem to be too many employers looking for that (though if you know of any, please point me too them :-).
Since I'm way out in stix of SoCal, next to the border, in the desert, in the middle of a mainly agricultural community to have access to all of the good employers/jobs I'd have to move up to the Bay, which isn't too bad (but it's SOOO expensive). I don't mind where I live so much...I just mind that the learning opportunities I have are so limited (so I end up having to find my own ways to teach myself, but that process is a lot slower than having a teacher, aka a willing co-worker, help guide you).
Key takeway though from this thread so far: Don't cash out your 401K and possibly put your family in a precarious position. Having a Happy Dad is important, but so is providing for your family. I would start small and be consistent with the activities you mentioned and treat them like projects. While I tend to forget (until I remember)...if you're consistent with your actions over a period of time you'll be amazed at how much you'll accomplish (of course this is compounded by family time, which takes away from the time you could use, but even if there's just one day a week that you can have some "Daddy Alone Time" that everyone is aware of, and the wife can be your buffer, then that'd be a good start :-).
Good luck buddy (it's tough I know!)