I'm back, apologize for the late update as bread & butter matter took over my fun times.

As this working with lethal voltage, I'm in the middle of building the prototype, even its very simple circuit, to accommodate easy yet as safe as possible for measurements, and maybe for upcoming minor tweaks/changes if needed. And possibly Duak's version too.
For basic measurements to capture the initial turn on condition, attached below is my initial setup plan, is this suffice ?
A DSO will be used in Single-Shot mode, still thinking about the triggering setup.
Appreciate any comment/feedback regarding this setup arrangement if any, thanks in advance.