Form and rules
How it works
Use will for spontaneous decisions, offers, promises and predictions mainly based on opinion.
Use be going to for intentions decided before speaking and predictions based on present evidence.
Use the present continuous for organized arrangements involving a future time, place or other person.
More than one future form can sometimes be possible, but the meaning changes with the speaker's viewpoint.
Do not choose a form only because you see tomorrow or next week; identify whether the sentence expresses decision, intention, evidence or arrangement.