The problem is that it varies significantly from person to person. Genetics can play a big part in determining if you develop complications. Studies have shown definitively that people with high A1cs are more likely to develop complications, but there will always be the odd person who has a high A1c yet never develops any major problems.
Some people develop complications very quickly, but others may never develop them. Still others may develop them 20-30 years later. I’m sorry I don’t have a hard, fast number that shows when or if you’ll develop them, but everyone’s body works a little differently. Some people are predisposed to complications and others are better protected.
Here’s a study that shows the blood sugar levels of people without diabetes: Continuous Glucose Profiles in Healthy Subjects under Everyday Life Conditions and after Different Meals - PMC
I’d aim for trying to stay in the same range- especially near the mean. That being said, don’t beat yourself up too much if you can’t obtain those numbers. Just try your best.