The best reason why newly divorced parents should not handover young children is so the child doesn’t feel conflicted.
Children love each parent unconditionally, they don’t get a choice so ensuring there is no physical handover at first means the child doesn’t feel torn between you.
Perhaps relaying this message to your ex she will understand this is for the sake of your child.
You two are adults, you can deal with your emotions that you’ve created from this situation, it is unfair to put your child in a stressful situation she didn’t create until you two can be civil with one another in front of her.