Berry’s pay scale is listed on the profile page of this site and gives average miles of 155,000 (point to point, straight line distance in SM). So you get a base salary of $32k + $15.5k mileage = $47.5k. That’s an average, could be more, could be less. Day Off pay means if you are away from home on a sat/sun you get $200 each day. It works out to roughly every 4 weekends you’re required to be “on call”. There is no overtime but I guess you can consider picking up weekends as Overtime, however, FOs typically do not want to give up weekends because that’s $400.
On Demand Cargo is feast/famine style. You may have 10 days running around on minimum rest followed by 10 of sitting at home doing nothing. Paychecks vary too because of this.
If all you want to do is get your 1,500 hrs and bounce, that’s fine if you are up front with that and put in their handshake agreement of 1 year. Hours vary too; one year could be 300 the next could be 800+. 2021 is looking to shape up as one of those 800+ years. Getting hired at 500 hrs is unlikely without an internal recommendation, but doesn’t hurt to try. If it’s a good year, You’ll make more as an FO at Berry than a regional.