This is true. There is no connection between snapshot date selection and the AGS campaign.
Each developer must select a snapshot date for their DAC based upon the progress they have made and their confidence that they are ready.
We picked 2/28 because we thought we would soon be ready. Then we discovered that more work was necessary and had to insert a 10 week delay to develop DPOS.
We recommend that developers finish testing before picking a snapshot date in the future.