Form and rules
How it works
Will often expresses spontaneous decisions, promises and opinion-based predictions; going to expresses prior intention or evidence-based prediction.
Present continuous is common for arranged personal events, while present simple is common for timetables and fixed schedules.
Future continuous presents an activity as in progress or as part of an expected future routine.
Future perfect presents completion before a future reference point; future perfect continuous emphasizes duration up to that point.
Several future forms may be grammatically possible in one situation, but each frames the event differently, so choose according to meaning rather than a time word alone.