Community College Daily reports:
The deadline to submit requests differs from office to office but is generally sometime between March 3 and March 17. The deadline for a specific office can be found on the senator’s official Senate website (the URL will contain senate.gov). Not all senators will be accepting CDS requests, and submitting a request certainly does not guarantee that it will ultimately be included in the final appropriations bill.
Requests for project funding are submitted to individual offices via an online form, which can also be found on the member’s website. The forms may be referred to in other ways, including as “appropriations requests,” “funding requests” or “community project funding requests.”
https://www.ccdaily.com/2023/02/washington-watch-senate-offices-now-accepting-requests-for-fy24-earmarks/