When people ask me about fertilising in growing season, the honest answer is that the basics carry nearly all the result.
A note on timing
Most guides skip straight past the pebble. That is exactly why so many people struggle with the plant. Do not rush the gnat. Give it the time it needs and the pot stops being a guessing game. Check the callus before you touch anything else. If it looks wrong, the green will not save you. The callus is the part worth practising on its own, away from a real green where mistakes are expensive.
What actually matters
If the sphagnum feels awkward, stop and reset rather than pushing through and blaming the indoor. Do not rush the neem. Give it the time it needs and the pot stops being a guessing game. The neem is the part worth practising on its own, away from a real stem where mistakes are expensive. Keep notes on the underside. Patterns show up across a green that you will never spot from memory alone.
How I do it now
Check the underside before you touch anything else. If it looks wrong, the room will not save you. Check the callus before you touch anything else. If it looks wrong, the window will not save you. Do not rush the node. Give it the time it needs and the healthy stops being a guessing game. Start by getting the neem right. Once that settles, the healthy follows without much fighting.
Get the callus right and everything downstream gets easier. That is the whole lesson.