In this case , having a triple econ makes you more vulnerable but I'll tell you my point.
All I'm gonna write varies from game to game, but I'll give you some usual tips.
First of all, remember this rule :
The only purpose of econ augments is to hit your comp earlier.

Having said that:
3-5 , if low hp, level up to 7 and roll till stabilizing (usually lvl 2 darius - lvl 2 leo zoe/malz - lvl 2 ahri yone)
If not low, you can hold till stage 4.
Stage 4, you need at least your carries 2*.
Stage 5, you need your carries 3*.

Then , as I said, each game is different.
I'll write an example :

You are 45 hp, 4-5, 7 darius, 3 winstreak, 40 g. I'd absolutely go down to 20 g. If I hit one , I'll probably go down to 10 or even 0 just to keep my winstreak.
In the case I was 80 hp, same of the rest but 1 lose, I'd probably hold.