even if you WERE intent on doing 5 days 9-3, there will be weekends, surely? So you could theoretically do 5 days.
In practice, of course this isn't how it works. We certainly don't do 9-3 every day. We are much more relaxed, we are often still waking up at 9. But THEN we don't clock off at 3, either, nor at weekends. Learning really does take place all the time, all I think most kids need is not to be put off.
I think you are actually very wise to start getting your head around it now, when your son is very young. I did 90% of my reading and converting of dp around this time, and it makes it all a lot easier now, tbh. I have been chewing over the pros and cons for long enough now to be very confident with the decision. Also, although we are, and I think, sadly, always will get a lot of opposition from my in laws, no one can say that this is a whim.
Can I recommend some books? If you haven't already looked at John Holt's stuff, he is great. - this gives you a taste (I think that there is a link to most of the issues of GWS on the server of some HEing magazine but I couldn't find it just now)
Also, Grace Llewellyn's teenage liberation handbook is really good. I know your son is only 1. Get it for YOU and read it to get your head around what HEing could have meant for you.