Hi Marco,
at DTP , i think you can maintain routine which exclude first 3000 requests.
You may need to pass the request id which will be greater than req number (3000th request number) get form table which stored psa request and use conditions. it may work.
take abaper help to build small logic to exclude first 3000 request.
for dtp routine filter you can search from google you may get useful information.
Thanks