Try creating a formula field that'll help you check whether the record has a date that's 8 or 9 days away:

IF(
OR(
DATETIME_DIFF(
Date,
TODAY(),
'days'
) = 8,
DATETIME_DIFF(
Date,
TODAY(),
'days'
) = 9
),
'True',
'False'
)
Then, create an automation that runs once a week and give it the following actions:
1. Find Record action to look for all the records that have a formula field output of 'True'
2. Repeating group that takes the output of the 'Find Record' action
3. Google Sheets Append Row per item in the group
Should do what you need!

Link to base