Hire through a nanny agency, they will facilitate all of the logistics and making sure it works out

Make sure that you're on the same page about whether you're paying taxes.
Get on the same page about how to introduce food and other similar things.
Have a discussion now about outings, budget, covid exposure, etc.

Repost in nanny forum.

What I know about shares is that it’s better to be at just one home - the one with the most outdoor space. Get a nanny who is experienced in shares and set rules with the other parents on where the nanny can take the children. The nanny needs to be paid her full rate (guaranteed hours) regardless of picking up early, family trips, days you keep your baby home. If you set the schedule at 40 hours, you pay 40 hours regardless.

Discuss covid precautions with the other family and the nanny. Agree ahead of time with the other family on nanny gifts or bonuses.

We're considering going in on a nanny share with a neighbor we don't know well, but who lives a few blocks away. My little one is a few weeks older than the neighbor's daughter, but they will both be about five months when we start. We'd split time at each house, each pay a portion of the hourly rate and split vacation and any additional expenses. Other than finding a nanny who is comfortable handling two infants, what do we need to think through logistically? How can we structure this in a way to limit any friction? For anyone who has done a share, is there anything you wished you'd worked out in advance that you did not?