So I have a very informative post over here, be sure to take a look and give me a like on that post.
Post #1 and #277 are the most important.
However I’ll summerize it quickly and you can learn more in detail from there.
Download photone app
Get a piece of regular printer paper and cover your front camera on your phone.
Set the app to sunlight (not led or full spectrum)
Take a canopy average.
Jot that average DLI down.
Think about what stage of growth your plant is in.