I have never found the need for a night time temp drop with Heliamphora.... that is mostly tribal knowledge.
While it may be beneficial, it is definitely not required.
I do recommend not letting temps exceed 78f... while they can grow in temps higher than that, failure rates rise dramatically.
If that is nutans "giant" (likely) you will outgrow that tank in a year...
Welcome to the world of Heliamphora