I’m no expert, but here’s what I’ve gathered...
SCOTUS will issue its formal acceptance of the case, laying out the question and any formalities (who is involved, scheduling, etc.).
DC will submit its brief.
Heller will submit his response.
DC will submit a response to the response.
Amicus briefs will be accepted.
Oral arguments, lasting no more than 1 hour, will be scheduled and held.
SCOTUS will issue a verdict, probably with explanation, and possibly with dissent explanation, no later than 1 year from now (probably sooner).
SCOTUS will set dates and requirements in stone, all parties submitting strictly thereto.
SCOTUS will do whatever it wants.
And the rest of us rabble will spend a lot of energy in the intervening periods blathering on about stuff we don’t know.
Yeah, right! (THanks for the timeline.)