Unfortunately there is no way around getting 1000 hours 121 as an FO before upgrading. I came with 11K PIC on B737 and still watch everyone from the right seat. So plan on at least 2 years in the right seat unless you want to fly for a regional. Anyways, if you land a job with a major airline you have to start as an FO anyways. Usually the few jobs that offer DEC are not worth it compared to a job at a major/legacy airline. Good luck!