I wish I hadn't had to (for financial reasons) send DD to nursery at 11 months. She was there three full days a week and with her grandmother the other two. Granted there was part of me that enjoyed the break from toddler parenting, as I never got one overnight (cosleeping, breastfeeding through the night well into the preschool years) or at the weekend. But mostly it was just awful for both of us. She never settled well at all, which makes sense now as it turns out she's autistic - back then she was just labelled a 'high need' baby/toddler - and she has never coped well with nursery/preschool/school. If I could have kept her with me until at least two years old, I would have done. I think she'd have gotten something out of part-time nursery perhaps at 2 though, and certainly at 3. It probably wouldn't have helped her in the long run to keep her at home with me until she started primary school.
Obviously most kids aren't like mine, most will settle after a while but as others have said they get so much more out of it after 2. Before that they really just want to be with the familiar trusted adults who've been there since they were born (mum, dad, maybe grandparents etc).
But given DD's difficulties, I got a unique insight into nursery life. Our nursery was wonderful at recognising how hard she was finding it to settle and encouraged me to be in the building with her as much as needed. So even after I was back at work, after our rather unsuccessful attempts at settling before I was due to go back, I was there for up to an hour in the morning and also in the evening - autism means transitions are difficult so, although she was thrilled to see me when I came back for her, she struggled to leave quickly! So we'd sit and have a cuddle, she'd have some milk from me, we'd read a book, she'd want to play with things in the room that she couldn't enjoy in the same way when I wasn't there to help her feel safe.
This meant that I sat and watched many drop-offs in the morning. Yes many kids were fine, even at 12 months old, and settled really well. But a significant minority didn't, they'd sit there and sob and not even really have anyone actually try to comfort them because the keyworkers had learned that they couldn't really do anything other than wait it out. These kids just wanted their parent to come back. I was also there at the end of the day, when these kids were being collected, and watched the staff breezily tell the parent that they'd been absolutely fine all day, settled really quickly as soon as the parent had gone, etc etc. Which made the parent feel better, obviously. Which is why they do it. But IT WASN'T TRUE. So I don't believe that all nurseries and their staff are 'magic', at least not for all children.
If I had my time again and any choice in the matter, I would have stayed at home with her until 2 or 3 and then gone back to work part-time. If you have that option OP it is definitely worth considering. Listen to your gut.