How do I know how hungry I’ll be?

In the urge jar training, Brooke mentions including in our protocol how MUCH we’ll eat at a given meal time.

Thing is, I’m not sure how hungry I’ll be. I’m at my goal weight, and on top of that, I’m breastfeeding. Because of the latter, I’m very conscious of making sure I eat when my body is hungry.

I feel like planning for an amount at a given meal is tricky to plan for since I’m not always certain how hungry I’ll be. At the stage I’m at, should I simply exclude an “amount” on my protocol and just eat until I feel satisfied on the hunger scale?