Start tracking your forage, via trap and observation. If it appears to be disappearing especially in one size range or another you'll start to see a trend. From there you can remove LMB. You can also begin tracking the Wr of the bass you catch.

However, if larger bass are your goal, I'd remove all but the best preforming bass of each year class that you catch. The original stockers can stay, but any bass actually born in your pond can be removed except those that seem to have the best growth compared to others of the same age. This can get tricky though as the under preformers of one year class can overlap with the high performers of the following year class.