I looked in June/July for an October start.
Nannyshare: pros and cons.
Cons: There is no doubt it's far easier to have your own nanny. If you have a share you have to compromise on holiday dates, compromise on activities, and you have to do pick up/drop off at the other family's house half the time (unless they are happy for you to be host) which will add to your time for getting ready in the morning/commuting time.
There is no guarantee that your DC will get on - and most 1 year olds aren't really all that sociable anyway tbh. Obviously there will be some dilution of care - my child was quite difficult big understatement at that age, and that was one of the reasons we decided against a share, as we didn't think it was really fair on any nanny. If you have an easygoing child this may not be such an issue. And as others have said, it's normal for nannies to look after 2 children anyway.
Bear in mind nannyshares can break down when one family has another baby, and the nanny might stick with the other family rather than you, so might not be the best option if you want long term continuity (however you you can't guarantee that in any case).
You could look for a nannyshare with older school age child(ren) - this would mean your DC would get sole care a lot of the day, and might benefit from the company of older children post school - but your DC would be doing the school run every day which cuts down time available for activities and might mean they sleep at the "wrong" times (if a set nap schedule is important to you).
NWOC could work but dilution of care still applies, and the reduction in cost tends to be less than a true nannyshare - only about 20% discount rather than 40%. And there aren't that many of them so you get less choice of nanny.
Pros: On the other hand, a share is a LOT cheaper - about 60% of the cost of sole family. Some nannies prefer a share as they earn c. 12 net/hr rather than 10 net. And it might teach your PFB to share, wait etc - whereas a sole charge nanny can mean your DC get used to the world revolving around them alone! And maybe you'd get lucky and the DC would be the best of friends.
So I think it really depends on your finances and what your child is like/how flexible you are. We chose not to share as finances are not that tight and it was important to us to have everything based at our house, and around our/DD's needs. For a lot of people the cost savings may be worth the compromises however.
I asked on MN whether it was worth doing a nannyshare if we could afford a nanny to ourselves, purely for the social benefits to DD - and the answer was a resounding No. With hindsight that was absolutely right.