Bop I have no experience of adoption (my mum was adopted but it has no relevance here). I am a mum of 3 children though.
Stay strong. You should expect a rough ride for the first few days at least. Thinking back to having my first baby, it took me 18 months to feel like I knew what I was doing.
I had stuff all over the house, my house. Not the stuff I had lovingly prepared and bought but all manner of stuff from other people who meant well but that I was not expecting. I wanted to shut out the world and shut out all this stuff and get back to normal. And I couldn't.
Look at it long term. Say to yourself that each day is part of the learning curve and that it will be months for it to settle. Reassure yourself that it will be fine as you have cared for these great kids before and enjoyed them and it will be that again.
For now, its upside down. Inside out. Expect to feel like you wished you'd never done it and that you'll never cope.
Then you will cope.
Then you will realise that none of it matters, the hair clips, the rooms, the bags of stuff.
What matters is that your children stay secure (that means keeping the 40 pairs of pants within sight) and stay loved.
You will be a family and you are doing just fine. Your feelings are just like mine when I brought home my first child seven years ago.
Stay strong.
p.s. creep in and look at them when they are sleeping.
p.p.s. expect a broken night.