Safe Levels of Nitrites (NO2-) for Cycling Tank (PLANTS ONLY for now)

[Myrium]

My beloved cat's obsession with random bubbles in my room humidifier has led me on an odyssey/new obsession to build a fancy guppy bachelor pad/tiny shrimp aquarium for her terrorize... er... watch VERY CLOSELY.  May need to start a separate thread on the availability/construction of cat-proof aquarium lids.

Current plan is to (continue to) cycle the tank with plants only.  When ammonia/nitrites go to zero, I'll add a trio of guppies (male), and build the bio-load slowly from there, as the tank chemistry will support.  The final tank (10 gallon) will be 6-8 guppies (bachelors), a colony of neocaridina shrimp, and maybe a rabbit snail or two??  

Question I have not been able to answer:  At what NITRITE (NO2-) level do I need to do a water change to protect the health of the PLANTS?  There is NO ANIMAL LIFE in this aquarium (yet).

I have resisted water changes thus far because the total ammonia levels (API master test kit) barely reached 0.5 ppm today (this is the max so far... usually closer to 0.25ppm, steady) and I am seeing nitrates being produced. Nitrates finally reached 20 ppm this morning, after being stuck at 5ppm for a few days. (There are no nitrates in the tap water, and I haven't added any water since set up.)  My concern is that the nitrites spiked to 2 ppm this morning.  According to:  https://www.aquariumcoop.com/blogs/aquarium/fish-tank-cycling ("Cycling with Plants" section) you're cycled when you see new plant growth.  The cycling is NOT done in my case, because although I do have plant growth, I also have high levels of nitrites (and some ammonia).

I don't want high nitrite levels to hurt the plants. Although they are growing, they seem to be quite fragile yet: shipping from the Etsy Seller's place was TOUGH on them, even though the weather was mild. (I won't be doing that again!)  I don't want to reduce the nitrates if I don't have to for the sake of the plants.  The ammonia/nitrates (and root tabs) are all the plants have to eat until the Easy Green gets here (delayed until Monday 😢).

Current plant status:

• The lace leaf water sprites are growing fast enough to watch in real time (almost). All the leaves they arrived with are dead/dying, but they're putting out new shoots like kudzu... I might have a monster in a few weeks.  
• The leaves of the lemon bacopa turned from sickly yellow to either brown mush or green, and I am seeing new growth including baby leaves and a root that has embarked on an ambitious 2 inch journey to find the sand. The rest of the stem's roots are buried; he's just really high up and apparently chose the wrong career... But he's halfway there and I'm cheering for him (and avoiding the obvious pun).  
• The weeping moss MIGHT be growing? It's hard to tell, but I chopped it up and tied it to the spider wood decoration today anyway.
• The corkscrew vesuvius seems to be in stasis.  No additional leaf death beyond what was dead/dying when it got here, but also not sending out new leaves after 8 days.

Also, I have removed a dead bacopa leaf here and there, but have mostly left them as a source of ammonia for the bacteria.

What does the ACO hive mind suggest?  

Tank was sized at 1 gallon/pound of cat.  Added air stone to sponge filter after this pic was taken to improve performance, but at the cost of making it less interesting to cat.  Cloudy because mid setup (sand fines in water column).

This is the way it looks today.  Will be repositioning small rock in back corner to make it less of a death trap before the fish are added.

Examples of new growth... 

 

[Mmiller2001]

If this was me, I would be concerned I didn’t have enough plants and would quadruple the plant load in the tank. Hopefully the EG arrives soon and start dosing at half the recommended until the plants start growing.