Since she only brought the paperwork on Friday and then for the first day was away - as in child did not start as in the contract I would just contact her and say that you have changed your mind and that you do not feel that the relationship is going to work and to please come and pick up her deposit check. You might be surprised to find out she is just as relived as you are - one of the reasons she waited till the absolute last minute she could to bring the paperwork - she just mentally couldn't do it which is something you have alluded to. It also makes no sense if work offered her a job for 3 days, then she only needs 2 days of care then agrees to 3 - but that means three paid days, doesn't mean child will actually come the third day which while it is great to get paid for no care also means you will be weeks getting the child to settle in if he ever does since he will pick up on mom's apprehension.

The most fussy families tend to interview the most number of people before choosing one so she probably has some other names to fall back on so I wouldn't feel too badly about abandoning them. Doesn't sound like she wants to go to work anyways.

A family needing 4 days a week and comes with the insecurities is definitely a better fit for daycare.