18m big sister

Ca

How are y'all telling your kids around this age about the new baby? I don't know if my little one understands what's going on just yet but we try and talk about the baby in front of her and tell her she's going to be a big sister. I don't think she is understanding. She will be 23 months when baby is born and I don't want her to be blindsided by us bring home another baby?? Advice?