Here’s a method that can easily outperform 99.9% of people:
Step 1: Remove the lead weight from the lead clip on the main line (with hooks attached), and hang it on the hook. (If fishing with the lower hook touching the bottom and the upper hook suspended, hang it on the lower hook; if both hooks are on the bottom or the bait is heavy with a small float sinker, hang it on the upper hook.)
Step 2: Find the bottom by sliding the float up until it shows 2 scales.
Step 3: Return the lead weight from the hook to the lead clip, then start trimming the lead until the float shows 2 scales again.
Although this method is a bit old-school, it’s incredibly precise.