Answers to your questions may be quickly "OBE" as we have a large vacancy bid opening today which includes initial filling of the new Vegas and Orlando 737 bases. The latter base will have the greatest impact on EWR seniority as that is, by far, the commute of choice for over 1,000 UAL pilots living in FL. Right NOW, you can hold 737 Captain at any UAL base except Houston as soon as you are off probation with 500 UAL hours which is 12 months time. Assuming that 80% seniority is 737 CA lineholder seniority, that is currently at about '15/'16 hires at both EWR and IAD. Meanwhile, on the WB side you can hold 777 or 787 FO at any of the coastal bases (EWR, IAD, LAX, SFO) in your first year if it's not available in your newhire class. WB FO at places like ORD, IAH and DEN are all down to less than 2-3 years as well. Being a WB lineholder, however, requires closer to 70% than 80% seniority because the "G line" is usually higher with seasonal flying fluctuation that is greater than the NB fleets. So 777 or 787 FO lineholder in the coastal bases is probably in the 3-4 year range but can vary across fleets a bit. Again, all these numbers are changing rapidly...generally all coming DOWN in time. Good luck!