I think either/or of the situations above will work well.

Yes, trial days are SO important due to the dynamics of this type of work.

The chemistry must be excellent between the parents/child/Nanny if this arrangement is to fully work out.

Generally, you accept the job and then negotiate a week or two of a trial period.

Hi ,
Is this okay to ask for work trail period? I meant just spend one day with kids ( see how it’s goes)before accepting position.
Thanks