To the OP:

It's simple; apply everywhere that is hiring into anything that gets you MEL time. If that means starting out for a small 135 outfit in a 310, do it. Then go from there...

...135 Turbine (preferably) MEL SIC and upgrade.
... Part 91 corporate gig (if you like that niche or find a creampuff one).
... 121 Regionals or LCCs.
... then your 121 Major/Legacy.

It all else fails, go to AK; there are always flying jobs.
If the airline gig is your goal now, go for it, good luck. Your timing and earnings/QoL desires may mean to end up staying at a 91 gig making 150K because it fits your needs, or being a Regional lifer; not bad things, just perspective.

If I had to wager, if you want to be at a Major or Legacy 121 outfit, I'd say you're honestly looking at 5 to 7 years before you're interviewing at a major/legacy.