The phrase "after which time" refers to a specific point in time or event that marks the start of a subsequent occurrence. There are several alternatives to this phrase that convey the same meaning, such as "subsequent to," "following," or "later than". Other synonyms for this expression include "post," "thereafter," "at a later date," and "in the wake of." These synonyms can be useful when writing or speaking about chronological events, such as historical timelines, schedules or deadlines, as they convey a precise understanding of when something occurred and the subsequent impact of that event. Overall, choosing the right synonym depends on the context and tone of the piece of writing or conversation.