From the technical contribution side, we think enforcing creation days for proposals can introduce more complexity than what it solves.
On-chain proposals have a voting period of 3 days (Level 1), or 10 days (Level 2). That means that even on the worst-case scenario of creating a proposal at midnight Thursday (1-day delay → voting running Saturday-Sunday-Monday), there is 1 week-day overlap.
That is obviously non-ideal, and contributors should probably avoid it if possible. But in any other scenario, there are 2 or more voting days overlapping, which seems perfectly reasonable, especially for delegates, considering that generally there are multiple communications and steps before a proposal goes on-chain (allowing pre-analysis/decision).
From an operational point of view, we find it fundamental for delegates to follow closely the community on the forum because that is the main objective of the voting delegation feature of the Aave governance.