HEY SOMEONE STOLE THAT FROM ME!
TRUE STORY TO FOLLOW:
Pretty much same situation, back pre-ultrasounds you had to wait for the actually birth to find out unless you and some extra $$$ laying around as ultrasounds were not covered by most insurances and were very expensive at the time.
We had several girl names picked out when a family member asked me "just in case" its a boy what are you going to name it...
Well it didn't take me long to think about it. I said that sounds good to me. They looked puzzled (as they usually do when I speak)
Justin Case sounds good to me.

Well when he showed up I was NOT ALLOWED to name him that so I named him JUSTIN THOMAS instead.
Should have stuck to Justin Case. It fits his personality!

Tom