There are no fixed dates in .com/net/org land, it would depend on the registrar and IF there are no auction interest in the name and if there is any interest in the name it may not drop and simply be transferred to the new owner, or it will automatically be dropped and caught by the registrars partner (no one else would have a chance).
You'd be better finding who the registrars partner is i.e. snapnames, namejet, etc, and seeing what their drop procedure it, but it can be anywhere between 40 and 90 days depending who the registrar is.