With regards to an upgrade, it just depends on the TYPE of hours that one joins with. If you already have 3000+ hours on an EK type before joining, then you will need a total of 6000 and 3 years of service in EK to be eligible for command. You will pretty much bypass the guys on the seniority list, if they have not have checked all the boxes for command (6000 TT, 3000 on EK type) , and YOU have!
WF