Timeline
Cerena: 40 BBY (39 years old)
Carr: 25 BBY (24 years old)
Josh: 21 BBY (20 years old)
29 BBY
Cerena is chosen to be Shaelis' padawan.
21 BBY
Cerena is promoted to Jedi Knight and assigned to other duties.
19 BBY
Jedi Purge
18 BBY
Cerena is ambushed by stormtroopers and badly wounded.
9 BBY
Cerena decides to start looking for Force-sensitives.
Josh's parents' freighter is attacked and Josh flees the ship.
6 BBY
Cerena arrives on Mirial and meets Carr.
4 BBY
Cerena and Carr arrive on Rudrig. Josh joins them.
3 BBY
(early) Cerena and her apprentices are still training on Rudrig.