After about 1 year you get the chance to upgrade to business class.
Who they select depends on how many sick days/ absent days you have etc..eg if you are actually sick that is ok. It works on a point system so if you are calling in sick on weekends and certain trips all the time you will have really high points and prob won't get your upgrade for a while. Some crew have been in economy for 2-4 years. If you get an absent day it means that you have not called in sick and that you are just not turning up for you flight.
After business for a while prob about 2 years you can then go to first class or apply for fast track to SFS which means that if you are good you can only work the minimum of 3 months in First then go to SFS.
You can be SFS after 3 years and prop Purser by 5 years.
After 1 year with the company you can apply for other dept based in different companies.