- after you have spoken with the ambassadors - until you give the trumpet to the judge.

You can cast Town Portal as you like but you must not portal to Harmondale - because the Harmondale portal is inside the castle.

Note: I am always giving the trumpet to the judge. I don't know when the "quest 0 bug period" ends when you miss the battle in Tularean Forest or when you give the trumpet to a king.

As far as the lamps are concerned, I came both from Deyja and from Harmondale and I sometimes got the extra items and sometimes I did not. Also, you get either all extra items or none of them. If you find one lamp, be sure that the second lamp is also around.