A fair point, I was thinking we should consider something like the 20 day average based on coingecko opening price ending on a specific day.
I wondered about the launch day as the last time point, but maybe we use Monday the 5th, then we have a couple of days to modify the IIP (possibly as a reply @dylan 
) with New INDEX token numbers.
Then we have time to deploy the contracts / tokens and write the liquidity mining blog post before launch.