Because the FSA is prefunded by your employer, your full contribution will be available on the first day of the plan year OR the first effective date of your benefits eligibility.
If you are beginning a new 12-month plan year that begins on January 1st, your full contribution would be available on January 1st of each new plan year).
If you are a new hire starting after your employer's calendar plan year has already begun, your full contribution will be available to you on the first effective date that you are eligible for benefits. When a new plan year begins, your FSA contribution for that year will be available to you on the first day of the plan year.
For short plan years, please double-check the first day of your plan year with your employer. Your full FSA contribution will be available to you on that date.