> the data within those 30 days
This is a common misconception. The requirement is
> GDPR information must be provided without undue delay but at latest within one month. Only in reasoned cases may this one-month deadline be exceptionally exceeded.
The operative requirement is without undue delay, one month is a maximum on the definition of undue delay, not a minimum. Intentionally delaying compliance for the better part of a month after you have demonstrated the ability to send the data within seconds would undoubtedly constitute undue delay... (Some exceptions apply)