Enlist the help of the two older kids (within their capacity). For me, I had a 5 and 3 year old when my 3rd was born. The 5 year old was especially helpful with simple things that become much harder when you're outnumbered.

Not supervising the baby obviously, but basic tasks like fetching something from another room or keeping the middle kid entertained while you're occupied with the baby.

I may have gotten lucky, but hopefully your older 2 will be similarly helpful.