Normally I don't and certainly only consider it if the first child stays full time during mat leave so I get 1 plus the income otherwise you are really holding two spaces if the older child isn't even covering the cost of their space.

I base decisions on how much I think the family my change their minds and/or I will have an opening within 3 months of them needing it. Otherwise sometimes it is better to just cut ties and replace.

A year is a long time and not uncommon for a caregiver to not agree to hold spaces. Mom also has plenty of time to find a new placement too so it works for everyone and you are not out money. And sometimes it just works out you have a space when they need them.