titfer - I think you are overthinking it a bit, certainly for the early days. I've got DS1 2.11, and DS2 11 weeks.
We've stuck with DS1's routine, 7pm bath and 8pm sleep - he then wakes around 8am.
DS1 started playgroup when DS2 was a month old, he goes two afternoons a week and we go to a toddler music group early afternoon another day, so that is our structure for the week.
I do an hour of housework/tidying etc immediately after breakfast when DS2 tends to be sleeping, although obviously this doesn't happen all the time and certainly in the early weeks it was all very hit and miss.
Then I have some time with DS1 and he 'helps' me with jobs, or to get the dinner made and we play/read stories. DS1 spends a lot of time in the garden atm, he is in and out of the kitchen where I am busy.
Then lunch, and either playgroup, music or we pop out for a walk on the other two days.
From about 3-3.30 onwards we have tv, snacks, a film or whatever. DS1 dropped his nap when I was 4 months pregnant so this is his - and my! - relaxing time.
DS1 has his tea at around 5.30ish. If DH is going to be home by 6 then I push dinner back and we eat together.
Obviously this does vary, but I really recommend getting the dinner cooked in the morning, otherwise you run into trying to sort it out while you are dealing with a tired and grumpy toddler, a baby who wants to cluster feed and won't be put down, and all at the point in the day when you are running out of steam!
General tips:
Get a sling
Have somewhere to put the baby down in as many rooms as possible so that they can be with you. We have a moses basket in the living room, and the pram in the kitchen.
Use TV. I have it on before breakfast while I have a shower and we all get dressed, and then again in the pre-dinner patch. In the early days it was on more than that but I am trying to cut it back now.
Easy meals that can be cooked in advance. Stir-fry is actually about the worst because it needs dealing with in the 'witching-hour'. A casserole and some jacket potatoes is perfect, or bolognese - basically anything that you can do in advance and then ignore for a few hours.
Don't be hard on yourself! If you get an easy baby then it will be a breeze once you're over the first few weeks, if you get a velcro baby that wants to eat all the time like I've got then some days it can be really hard and I try not to beat myself up if DS1 ends up watching more TV than I would like him to.
Get a sling.
Use TV in the mornings and again towards the end of the day.