Make sure your ad does not say "new daycare" just opening or 5 spots open. do not give any information to lead parents to believe you are new (until they ask). People want a stable, smoothly running daycare 'new' is not a selling feature.

I always only advertised one space opening. Was true, implies you were otherwise full and that the spot was opening in the future when a current child left. I also never advertised "available immediately" why would a solid daycare have an empty space? why didn't they prefill it...did a family leave suddenly due to a problem with the daycare?

give a start date at least 2 weeks away, a month is good. most good families look for care in advance not last minute so you shouldn't lose any families,

also, I had numerous VERY different kijiji ads out at the same time (linked to different email accounts so they can't see other ads) cater one to the Montessori to draw in the families aware of it. cater another to moms on mat leave etc...capture different audiences.