If you get promoted do you put the date of your promotion on LinkedIn or do you just list your ending title for the duration of your employment at the company you work at? Ie: if you are hired at Amazon as sde2 and then 1yr later you make Sde3, would you list the 1yr as sde2 and the time as Sde3 or just list Sde3?
Probably useful to show promotions in your current company (useful for internal folks who may look you up) but not for your previous companies (too much clutter, fold all the details into a single position - your highest).
Remember to write a post to humbly gratefully announce it
No one cares.
Ending title always because there are couple instances where Ibhave jumped off the ship after got promoted.
That's my thought process
In your example, IMO it would be nice to put both. It shows that you got promoted quickly + career growth