Can't speak for Mesa, but with Envoy I would assume you can get a class date very quickly. Also you should be able to hold DFW right away.
Mesa has lost some flying to Envoy and will probably lose more before all is said and done.
Companies plan for Envoy is to make it a revolving door and one of the few ways to AA. Currently advertising 2.5 year upgrade and 6 years flow to AA. I've seen the numbers and they do work as long as management is able to execute their plan.
Absolute worst case for Envoy would be reduce fleet to only 40 aircraft which would be ~470 pilots. The expectation would be that we would have roughly 200-250 Capts who would never flow to AA and the FOs would then never upgrade. It would be a very painful process for all the employees to get Envoy to that point. However, once everything is done, a new hire could Expect to never upgrade, their time to flow would be ~18months. This plan is very unlikely at this point.
More then likely Envoy will be 180-200 aircraft with mostly 175s and some 145s. This will result in the 2.5 year upgrade and 6 years to flow. Some of this is dependent upon what PSA and PDT are able to accomplish in the next 4 years. Right now PDT is waiting for their 145 program to be approved and PSA is working through training bubble issues and aspen approval.
It is my understanding that DP wants to reduce the number of airlines providing feed, over time, to AA. Right now there are 9-10. I expect this to be reduced by 5 airlines over the next 6-7 years. I don't have any insight at this time on which ones he is looking at. However he will tolerate whoever can provide the feed with reasonable reliability and the right cost structure.
I do believe that things at Envoy are beginning to turn around, they do have a huge morale problem though. It will take some effort on managements part to make effective inroads on this problem. Much of there plan is solely based on their ability to execute.
Whether they can or not things are slowly moving at Envoy, but the pace is accelerating. I do believe now is a good time to get onboard the train.