to not add quite enough the first time, and add a little more later, rather than add too much and it just sloshes around and makes your wheel heavier than it needs to be.
I have found it's a fine art setting up tubeless tires. It all depends on your wheels (rims), tire brand/model, tape you use and how well it's taped, and the sealant brand. Different combos of any of these will mean a different level of ease or difficulty in setup and how well they stay sealed over time. Trust me..... I have 20+ wheel setups of varying size, type, etc under my belt :)
Tubeless can be a hassle at times, but I still feel they are well worth the effort (and occasional mess). Welcome to the tubeless tribe!
One more ounce in each tire did the trick!