If possible, learn why your ancestor “broke the rules” or went against tradition. I’m not certain why my wife’s Roman Catholic great-grandmother didn’t have her last two children christened as infants. She waited until they were nearly 7 and 8 which is unusual.
The baptisms were likely done then as she got married in a church ceremony a few weeks after her children were christened.
She could easily have had them christened at birth. They were born in Chicago in the 1910s—there would have been plenty of opportunities.