An underage (< 12 for girls, < 13 for boys) gentile child can be converted to Judaism under certain circumstances, but they have the right to renounce this conversion upon reaching adulthood.
My question is, is there a specific time limit for renouncing this infant conversion, after which it is no longer halachically possible to accomplish? For example, suppose Shimon was converted as an infant and just turned 13 years old today. He is strongly considering renouncing his conversion and living his life as a Gentile but wants to think about it a little more first. Is it sufficient for him to make his decision by sunset? Is it too late if he makes his final decision to renounce a week after his birthday? What if he lives most of his life as a Jew and then decides to renounce his conversion on his deathbed at age 85?
- Is there a specific "hard" length of time that a new adult has to renounce his underage conversion (e.g. a hour, one day, one week, five years, etc.)?
- Is the length of time based on a "reasonable" length of time which might vary based on circumstances like how educated they are or how independent they have become from their parents?
- Is the deadline based on further life milestones? For example, a child convert might be able to renounce at any time before getting married, even if they remain unmarried for decades, but once their are married to another Jew, their conversion is permanent.