When using the Daily note plugin’s template, the line responsible for drawing the current day marker circle on the timeline is this one:
<circle cx="{{date:DDD}}0" cy="44" r="30" stroke="black" stroke-width="7" fill="white" />
When using the Templater plugin, you would change that line to:
<circle cx="<% tp.date.now("DDD") %>0" cy="44" r="30" stroke="black" stroke-width="7" fill="white" />
Both “DDD” and the “DDDD” format suggested by @cabin.mooring would work (tested). But “DDDD” would create a leading 0 for the cx value, which isn’t necessary.