"Most" cows that calve early in your season, will always calve early. But, as I've said before - cows don't like to read the rules.
I have a specific calving "season" about 60 days. So, every year, I start breeding on the same date. Most of my early calvers will be on their 3rd heat cycle. Those that calved the end of my season, will be on their first cycle. So, any cow that doesn't settle first AI service (whether it's her 1st or 3rd cycle) ends up in the middle or later calving the following year's season. As long as they breed in the designated time frame, that's fine.