I remember freaking out about kind of the same thing while I was PG.. I couldn't fathom how I was supposed to get out of the house on time each morning when I was struggling as it was (with the three older kids). And I asked my boss for advice - she has 4 kids - and she said 'you just do it. you do what you have to do' And I thought 'pftt, that's not very helpful'... but as it turns out, it is exactly the truth

I went back when Pie was 9 weeks old but that was only one day a week. I think that helped... I kind of eased back into it, after a few weeks it was 2 days, then a month or two later it was three, then 4 (now I'm back to 2 for a while).

getting everything done... well, I don't! The housework definitely suffered, and if I end up back 4 days again after Christmas we will look at getting someone in to do the bathrooms once a week. We have a great repertoire now of quick & easy meals... and as for getting out of the house in the morning, I don't know how! but we managed fine. The best thing for me is to be really organised the night before - I get Pie's lunch, clothes etc ready, bag packed. I am usually up between 5 & 5:30 and aim to be out the door at 7:30 although it's usually more like 8.

Bottom line is, I found it much easier when I was actually doing it.
And I don't think you have to worry too much about trying to prepare yourself now KWIM? Just do what you have to now, then do what you have to later. Be gentle with yourself.
Best of luck