737 is slightly more junior (130 numbers) at DFW than the 320 as of 1 Jan. Which one is better? Who knows.
Here's my data: 6 months on property. 3 months to get through indoc, ground school, and IOE. 2 months of short call in NY. October was long call in DCA. Next month I have a line in DCA and I think I'll be able to hold it given the inbounds to DCA in December. DFW looks like it'll be possible with reasonable seniority mid-summer 2019 (I'm a commuter and do not plan to give up a line in DCA for SC in DFW).
There are dudes that were FOs for 20 years and sat short call for 12 years. It might take me 15-18 months to get DFW with the seniority that I want. I am 2.5% into a 20-year career with no complaints!