How many years of experience do we need to become IT Analysts?

Generally, minimum 4 years experience is required to be eligible for ITA promotion but in some cases like 2 consecutive A bands, you can be eligible and can ask your manager to raise your promotion request in system

3 years is the bare minimum. Just go and talk to your manager about promotion, highlighting your achievements and the quality of work you have delivered during these years.

You need to complete 4 years, ask your manager for promotion eligibility.