Do I need to specify my arrival date when applying for a Thai visa?

When applying for a Thai visa, you do not need to specify your arrival date at the time of application. Once your visa is approved, it is valid from that approval date, and you can enter Thailand at a later time, within the validity period. Generally, you will not need to 'collect' the visa physically; instead, it is often issued as a PDF document that you present each time you enter Thailand during the five-year validity of the visa.