The phrase "always-already" is used to stress that a process being described is not seen as having an identifiable beginning. Less a way of making a claim than a way to studiously avoid making a claim about temporality. For example, Althusser regarded individuals as always-already subjects of ideology, their place in society being determined long before they are aware of it or even born.
Kind of an odd phrase to an English speaker (at least to me), but it's not English in origin - it's a literal translation of the phrase "immer schon", used frequently by Martin Heidegger. I assume it's more intuitive in German.