An employee gets a step increase on their Salary Eligibility Date (SED).  An SED occurs:

1.     The beginning of the month following the annual anniversary of their date of hire until the top step of the salary range is reached;
2.     The beginning of the month following 6 months after a promotion and every year after that until the top step of the salary range is reached.

Because the effective date of a step increase is at the beginning of the month following the anniversary date, and the pay is received at the beginning of the month following the month of the effective date, you will not see the impact of a step increase until 2 months after your anniversary date. For example, if your hire date is March 3, your SED would be April 1. You received pay for the month of April on May 1, so you would see the step increase in your pay on May 1.