No worries - good on you for stepping out of your comfort zone to give it a try!
A different approach you could take that would work in blueprints: create a grid of invisible cubes in front of the plate. As you’re painting the pixels, also do line traces against the grid and destroy any cubes you hit. Then your progress will be equal to:
number_of_cubes_destroyed / starting_number_of_cubes
The smaller each cube is on the grid, the more accurate your progress will be, though it’ll also take more processing power.
Hope this helps!