Taking share acquisition date as avg across all vesting dates for CGT in section 104

Hey Admins, Context: I have number of shares in the same company vested to me in USD at multiple time points over the period of roughly 5 years. I sold them in Fy23-24. To ease the calculation of CGT I want to use one acquisition date for the whole lot for the purpose of converting USD to GBP to calculate my cost basis for S104 holdings. Can I use the acquisition date as the date where I got half of the total shares so it is somewhere in middle (though it is possible on that date no share actually vested). And then apply exchange rate for that date to calculate cost basis. Starting/ending acquisition dates won't be fair to use as numerous shares and long time period.

Hi,
Please have a look at helpsheet HS284.
HS284 Shares and Capital Gains Tax (2024)
Thank you.