If their application process has a place to disclose it, do so there. If not, do not volunteer the info. The process-driven disclosure should keep the information separate from hiring decisions, which is what you want as it supports their hiring needs without attaching quotas to you personally. After all, quotas can cut both directions.
Once you are hired, disclose it on the very first day, with a letter from a doctor that details what accommodations are required for you to do the job. Unless you don't need accommodations, in which case do not disclose it.
It may be a good idea to disclose it anyway, depending on the regulatory environment. In many countries, having a disability makes you more difficult to fire. This is especially true if they are trying to fire you for reasons that are even partially related to how your disability manifests.