An individual would be allowed to carry forward unused portions of their annual contribution limit up to a maximum of $8,000. This means that an individual contributing less than $8,000 in a given year could contribute the unused amount (i.e., $8,000 less their contribution in that year) in a subsequent year on top of their annual contribution limit of $8,000 (subject to their lifetime contribution limit). For example, an individual contributing $5,000 to an FHSA in 2023 would be allowed to contribute $11,000 in 2024 (i.e., $8,000 plus the remaining $3,000 from 2023). Carry-forward amounts would only start accumulating after an individual opens an FHSA for the first time.

Sounds like it accumulates but only after you open an account.