Yes, it is clear that time passes slower on the island. Otherwise, how could the baby possibly be explained.

As for the length of time between rescue and trial, almost anything is plausible. In Atlanta we have a guy who killed 3 people while escaping from a courtroom in front of many witnesses, and he confessed. That was 3 years ago and he has not gone to trial yet.

It has taken 60+ episodes to cover 100 days on the island. It seems very unlikely that they will spend many more days there. So Aaron leaves the island at age 3 or 4 months, after they were all missing for one to three years, and it took them 2 years after rescue to start the trial. That seems most likely.