I think you would need to budget for a couple years at the regionals. There are ways to ease that pain (reserve orders while an FO), but that FO time is designed to prepare you to fly as a 121 PIC.
It's not impossible that you could get out, get hired at the big 6 ASAP, and then go back to finish your active duty retirement. Just recommend completing your probation year first.
As an aside, have you thought of the Gov? USAJobs lately has had many interesting flying jobs you're well qualified for. Examples would be 737's for the Nuclear Regulatory Agency, King Air 350's for NCIS in DC area, King Air/Bell 407 for Bonneville Power Authority in Oregon, airspace inspections pilots in multiple locations. Even my agency (CBP) is seeing an uptick in fixed wing with additional KA350 deliveries. With the SSR (Special Salary Rate) that most agencies are paying now it's much more attractive. Many benefits when you buy back your Mil time.
It's worth a scroll though USAJobs. You may find something cool exactly where you want to be.