Ok I will not make any comments on my progress :D (let's just say I stalled).
I got that wrong, 868 is the total number of squares, I only need 449 for the background. Anyway here's my spreadsheet
It's just a simple countif to tally the squares, and I timed myself so I can work out the time needed to make the squares. Joining them together is going to be another battle that I'm not looking forward to :D