I keep it simple. Get yourself a Caliber IV humidity meter. There is no formula. And 15 mins in way too much, I think. You are trying to control humidity in the jar.
Leaving it open is not a burp.
So, here is my simple plan and it varies my humidity, not time.
I strip the leaves before I cut the plant, it is just easier for me.
I leave stem below all flowers, enough to hang them on a wire, and space them out,
Here it is not time based, but stem based. When the stem is dry enough to break over, but not snap off, it is ready for the next step.
All the stems are different sizes, but, I group by big and small. Small stems are ready first,
Ready for what? Not the jars, just yet.
Strip the buds from the stems and put into a paper bag with the Caliber. Let is sit for 1 hour.
If the humidity is above 70 RH I bring it all out on a screen for a day, maybe. (you get so you can do this by feel, almost)
I want it to stay in the bag in the 60s down to the high 50s RH
Then I half fill, 1 liter mason jars. You want leave room for shaking. And throw in the Caliber and seal the jar.
Check in one hour.
If the RH is back in the 60s, it goes back in the paper bag, if it is in the 70s, out on the screen again.
My gate is to have mid 50s RH, and no lower than 53 RH to begin the cure.
Seems like a lot trouble? It can all be ruined here with mold, and I have done that.
Now, finally, I can begin the 30 day routine.
Each day, each jar, I shake vigorously and open it for a deep smell. This is why we burp. If that smell is anything but sweet hay smell it comes out on the screen again.
It doesn't matter about the RH, but you will find it probably spiked in that one jar, but it does not reset the 30 day clock.
Bring it back in with mid-50s RH holding in the jar,
The first week really matters for this.
After you get the jars stable with RH, it is just a matter of shaking, sniffing and closing for 30 days,
After that the stuff can stay sealed in the dark, indefinitely.
If you get below 45% it can't be recovered down in the cells and it won't transform, ie, cure, very well.