I believe some 380 DEPs are expected this year, but how many, or whether they’ve all been given their offers already, I do not know.
It is very difficult for anyone to advise whether jumping from one airline to another is the right thing for the individual to do. I personally do not think BA has been the ‘be all and end all’ for a very long time, but people still keep joining, and I have never worked for another airline so what do I know? That being said, if you are ever going to join BA, sooner is almost always better than later. If you have left it until later, it is practically guaranteed you will regret it for a period of time, as the bottom of the seniority list on any fleet is not that much fun. Some fleets have better junior lifestyles than others, and you’ll stay junior for differing periods of time on the different fleets too. That’s before you even consider the financial side of things.