Early Neptune/Anvil Plans???

At the start of 1944, when SHAEF took over the Overlord plannning from COSSAC the original target date for Op Neptune was 1 May & the Op. Anvil date was 1 April. Does anyone here have any knowledge of the early plans for either operation for the April & May dates? I’ve seen a few details mentioned here & there but nothing that made clear the nature of the operations as planned up to March 1944.

Thanks For any help.