When in the game can you get to House Zu Heltzer?

I just finished the mission with the Kraken where I got the spear, and now I'm back in the city. How much longer until I am able to do the befriending the kurzicks quest?

Complete the Sunjiang District mission and you'll be taken to Maatu Keep. Speak with Jamei for the quests to Cavalon/HzH. Do that and you'll receive the befriending quest.

Wow, 10,000 faction. x_x

You'll be able to enter House zu Heltzer/Cavalon without doing the Befriending the Kurzick/Luxon quest, all that quest does is give you 10,000xp for showing the NPC your 10,000 Faction. Just do the quests picked up in either town; you'll have plenty of faction.

The mission progression to get to HzH/Cavalon is:

• Vizunah Square
• Nahpui Quarter
• Tahnnakai Temple
• Arborstone
• Boreas Seabed
• Sunjiang District
• Speak with Jamei in Maatu Keep and pick up the desired quest.

For further info, check out this link:
Mission Overviews (Factions)